N15 4-6-0 LSWR Urie & SR Maunsell King Arthur 30448 – 30457, 30736 – 30755 & 30763 – 30806

N15 1

n15 2



Power Classification 5P
Introduced 1918 – 1927
Designer Urie & Maunsell
Company LSWR & SR
Weight – Loco 30448 – 30452 – 80t 19cwt

30453 – 30457 – 79t 18cwt

30736 – 30755 –  80t 7cwt

30763 – 30792 – 80t 19cwt

30793 – 30806 – 81t 17cwt

               Tender 30448 – 30452 – 49t 3cwt

30453 – 30457 – 49t 3cwt

30736 – 30755 – 57t 16cwt

30763 – 30792 – 57t 11cwt

30793 – 30806 – 41t 5cwt

Driving Wheels 6ft 7ins
Boiler Pressure 30736 – 30755 – 180psi superheated

Remainder – 200psi

Cylinders 30736 – 30755 – Inside – 22in x 28in

Remainder – Inside – 20.5in x 28in

Tractive Effort 30736 – 30755 – 26,245lbf

Remainder – 23,915lbf

Valve Gear Walschaert (piston valve)


Urie completed his H15 class mixed-traffic 4-6-0 design in 1913 and the prototype was built in August 1914. It showed a marked improvement in performance over Drummond’s LSWR T14 class 4-6-0 when tested on local and express passenger trains. The introduction of ten H15 engines into service coincided with the outbreak of the First World War, which prevented construction of further class members. Despite the interruption caused by the conflict, Urie anticipated that peacetime increases in passenger traffic would necessitate longer trains from London to the south-west of England. Passenger loadings on the heavy boat trains to the London and South Western Railway’s (LSWR) ports of Portsmouth, Weymouth and Southampton had been increasing prior to the war, and was beginning to overcome the capabilities of the LSWR’s passenger locomotive fleet. His response was to produce a modern, standard express passenger design similar to the H15.

 t14 T14 class introduced in 1911 by Drummond – only ten were built with the last withdrawn in 1951.
 h15 H15 class introduced in 1914 by Urie. The locomotive was developed by Maunsell with four different groups of design completed by 1925.
 n15 as new N15 class as first introduced by Urie in 1918.

Trials undertaken in 1914 with the H15 class prototype had demonstrated to Urie that the basic design showed considerable speed potential on the Western section of the LSWR from Basingstoke westwards, and could form the basis of a powerful new class of 4-6-0 express passenger locomotive with larger 6 ft 7 in driving wheels. The LSWR required such a locomotive, which would need to cope with increasing train loads on this long and arduous route to the West Country. The result was the N15 class design, completed by Urie in 1917. It incorporated features from the H15 class, including eight-wheel double bogie tenders with outside plate frames over the wheels and exposed Walschaerts valve gear. High running plates along the boiler were retained for ease of oiling and maintenance.

This class and the earlier H15 class were probably the first LSWR locomotive to use Walschaert valve gear although the actual development of it goes back to 1844 when a young mechanic (Egide Walschaerts) designed it whilst he was employed by the Belgian State Railway. The benefit of this system over the previously widely used Stephenson valve gear was that The Walschaerts valve gear enabled the driver to operate the steam engine in a continuous range of settings from maximum economy to maximum power. There were other early examples in Britain but it was not until around the time that the H15, N15 and S15 class were introduced that it started to be used more widely in Britain. Drummond had first employed Walschaert valve gear on his T14 locomotives introduced in 1911.

The N15 design was approved by the LSWR management committee, though the order for construction was postponed until wartime control of raw materials was relaxed. Government approval was obtained in mid–1918, and Eastleigh Works began to produce the LSWR’s first new locomotive class since 1914.

30736-30755 were Urie’s original N15 design for the London & South Western Railway (LSWR) built in 1918-1923. The original engines were very poor steamers and in 1924 they were altered with improved draughting arangements. As such they were able to take their place within the new King Arthur class. However, they never quite matched the excellence of the later Maunsell engines. It was said that Maunsell was indignant when the SR directors decided to include them as part of the King Arthur class, saying that “names” would not improve their performance. They were fitted with eight-wheel tenders. They could be distinguished from other members of the class by their inside steam pipes and Drummond Urie safety valves.

In 1928 30736-30754 were further modified with new cylinders of reduced diameter.

Maunsell’s development of Urie’s design was introduced in 1925 (30453-30457). Originally intended to be rebuilds of Drummond’s 4-6-0 engines of the G14 class, they were in fact built as replacements, although they took the same numbers and were fitted with the eight-wheel tenders of the G14 class engines.

The modifications are attributed to Maunsell’s Chief Draughtsman Clayton, who had transferred to Ashford railway works in 1914 from Derby works. They were the result of cooperation between the South Eastern and Chatham Railway (SECR) and the Great Western Railway (GWR) when Maunsell was seconded to the Railway Executive Committee during the First World War. The aim was to create a series of standard freight and passenger locomotives for use throughout Britain, and meant that Clayton was privy to the latest GWR developments in steam design. These included streamlined steam passages, long-travel valves, the maximisation of power through reduced cylinder sizes and higher boiler pressure.

At the time of the appearance of the first of the class the Southern Railway had just appointed the country’s first Public Relations Officer to improve the company’s standing. He specified that the new class should have names connected with the legend of King Arthur and the Knights of the Round Table, and hence the class became known as the King Arthur class. They proved to be versatile engines and different variations were produced to enable them to work all over the SR system.

30448-30452 were built in 1925. They also carried the numbers of G14 class engines and received their tenders. They were built at Eastleigh to the LSWR loading gauges with the tall Drummond cab which always restricted them to working on the Western Section. The improved front-end layout applied to the first batch of Eastleigh Arthurs (E448–E457) ensured continuous fast running on flat sections of track around London, although their propensity for speed was sometimes compromised over the hilly terrain west of Salisbury. The inside bearings of the Drummond watercart tenders proved problematic, as they were too small for the load carried and suffered from water ingress. Despite these problems, their operational reliability prompted the management to arrange the visit of No. E449 Sir Torre to the Darlington Railway Centenary celebrations in July 1925. E449 also recorded speeds of up to 90 mph on the South West Mainline near Axminster in 1929. This proved that with the right components, Urie’s original design could perform well.

Introduced in 1925, (30763-30792) were ordered from the North British Locomotive Company in Glasgow because of a lack of production capacity due to repair and overhaul meant that was being undertaken at Eastleigh. They were known as Scotch Arthurs. Despite the successful use of modified N15 components to rebuild E448–E457, the mechanically similar Scotch Arthurs proved disappointing when put into service in 1925. The performance of those allocated to the Eastern section was indifferent, and failed to improve upon the double-headed ex-SECR 4-4-0s they were to replace. Reports of poor steaming and hot driving and tender wheel axleboxes were common from crewmen and shed fitters. After investigation, the problems were attributed to poor workmanship during construction as the North British Locomotive Company underquoted production costs to gain the contract. Defects were found in boiler construction across the batch, and necessitated six replacement boilers, re-riveting, re-fitting of tubes and replacement of firebox stays. The hot driving wheel axleboxes were caused by the main frames being out of alignment. A 1926 report suggested that all affected locomotives should be taken to Eastleigh for repair. Once repaired, the Scotch Arthurs proved as capable as the rest of the class in service.

Scotch Arthurs E763–E772 received new tenders between 1928 and 1930 in a series of tender exchanges with the Lord Nelson and LSWR S15 classes. This ensured that they could exchange their Urie 5,000 imp gal bogie tenders with the 4,000 imp gal Ashford design for use on the shorter Eastern section routes. Whilst useful for the roster clerks at Battersea shed, any transfer to the Western section was hampered because of their shorter range. By 1937, all had reverted to the Urie 5,000 imp gal bogie tenders, though E768–E772 were attached to new Maunsell flush-sided tenders with brake vacuum reservoirs fitted behind the coal space. These were again swapped with Maunsell LSWR-style bogie tenders fitted to the Lord Nelson class.

30793-30806 were introduced in 1926 and built at Eastleigh for the Central Section, but they were transferred elsewhere on electrification. They had detail alterations and six-wheel tenders.

The second batch of Eastleigh Arthurs displaced the ex-K class tanks and ex-LBSCR H2 Atlantic 4-4-2 locomotives on the Eastbourne and Bognor Regis routes respectively. They were well liked by crews and used on this part of the network until the arrival of electrification. E782 Sir Brian was used on the former Great Northern main line for performance trials against the SECR K and K1 class tanks following a railway accident at Sevenoaks, Kent in 1927. The tests were supervised by the London and North Eastern Railway’s CME, Sir Nigel Gresley, who commented that the class was unstable at high speeds. The instability was caused by motion hammerblow and exacerbated by irregularities in track-work. This caused excessive stress to the axleboxes and poor riding characteristics on the footplate. Despite this, the class benefited from an excellent maintenance regime.

Maunsell’s replacement Bulleid believed that there was little need to improve draughting on this series. However, reports of poor steaming with 792 Sir Hervis de Revel gave him an opportunity to trial a Lemaître multiple-jet blastpipe and wide-diameter chimney on a Maunsell Arthur in 1940. This did not enhance performance to the extent of 755 The Red Knight. Under British Railways ownership, the locomotive was re-fitted with the Maunsell chimney in 1952 with no further problems reported. In another wartime experiment, Bulleid fitted 783 Sir Gillemere with three thin stovepipe chimneys in 1940. These were set in a triangular formation to reduce visibility of exhaust from the air in response to attacks made by low-flying aircraft on Southern Railway trains. The stovepipes were reduced to two, producing a fierce exhaust blast that dislodged soot inside tunnels and under bridges. The experiment was discontinued in and the locomotive re-fitted with a Maunsell King Arthur chimney. The last experiment was with spark-arresting equipment in response to lineside fires caused by poor quality coal. 784 Sir Nerovens and 788 Sir Urre of the Mount were fitted with new wide-diameter chimneys in late 1947. Test-trains showed mixed results and the trials were stopped in 1951 after improvements in coal quality and the fitting of internal smokebox spark-arrestors.

The N15 class was intended to haul heavy expresses over the long LSWR mainlines between Waterloo, Weymouth, Exeter and Plymouth. Locomotives were changed at Salisbury before the upgrading of the South Western Mainline in 1922, when fast running through to Exeter was possible. The Southern Railway’s motive power re-organisation following the Grouping of 1923 saw the class allocated to sheds across the network and used on Bournemouth to Oxford cross-country trains. Operations were expanded to more restricted Central and Eastern section mainlines in 1925, and suitably modified class members hauled commuter and heavy boat trains from London Victoria to Dover Marine and expresses to Brighton. In 1931, E780 Sir Persant hauled the inaugural Bournemouth Belle Pullman train from Waterloo to Bournemouth West.

In peacetime, the class was occasionally used on fast freights from Southampton Docks, although it was common to see them at the head of freight and troop trains during the Second World War. Ten Urie Arthurs were transferred to the London and North Eastern Railway (LNER) in 1942, and were based at Heaton shed for use on freight and occasional passenger trains in the north east and southern Scotland. They returned to the Southern Railway in 1943 after the introduction of United States Army Transportation Corps S160 class 2-8-0s into service. A number were also loaned to the GWR between 1942 and 1943 to assist in bolstering the acute shortage of freight power on the GWR.


S160 class.


800 locomotives were constructed in 1942/3 in the USA and shipped to South Wales. The first 43 locomotives were transferred to the LNER works at Doncaster for completion, and later running in over the East Coast Main Line.

Allocation of the first half of the deliveries to UK railways-

  • 174 to the Great Western Railway
  • 168 to the London and North Eastern Railway
  • 50 to the London, Midland and Scottish Railway
  • 6 to the Southern Railway

The second batch of 400 S160’s were prepared for storage by USATC personnel at the Great Western’s Ebbw Junction locomotive depot in the immediate run-up to D-Day. After the D-Day invasion of Normandy, the locomotives deployed across Britain again began to be collected and be refurbished at Ebbw Junction in preparation for shipment to Europe

From 1945 the King Arthur class regularly deputised for Bulleid’s new pacifics, which were experiencing poor serviceability due to mechanical failures. The entire class came into British Railways ownership in 1948: they could be found in most areas of the Southern Region on medium-length expresses and stopping trains on the ex-LSWR mainline.

In 1926 the N15 class became the first in Britain equipped with smoke deflectors, with several designs tested. Experiments were undertaken throughout 1926 and included the fitting of a curved plate above the smokebox of E753 Melisande to channel air from below the chimney to lift the exhaust above the locomotive when on the move. E450 Sir Kay and E753 Sir Gillemere had air scoops attached to the chimney, whilst E772 Sir Percivale was fitted with large, square German-type smoke deflectors. Finally, E453 King Arthur was fitted with small, rectangular smoke deflectors fitted to the handrails on the smokebox sides. The experiments produced mixed results, and Maunsell requested the assistance of the University of London in staging wind tunnel tests. These resulted in a standard plate design, which was gradually fitted to the class from late 1927 onwards.

Under LSWR ownership, the N15s were initially well received by crews, though the batch soon gained a reputation for poor steaming on long runs. Through running of the class into Exeter was stopped in favour of engine changes at Salisbury, and Urie attributed the problem to poor driving technique. A series of trial runs changed this assumption, and demonstrated that steam pressure gradually decreased on the flat. The trials also revealed that the robust construction of the motion produced the heaviest hammerblow of any British locomotive class, and had caused cracked frames on the test locomotive.

Another criticism from locomotive crews concerned the exposed cab in bad weather, which necessitated the installation of a tarpaulin sheet over the rear of the cab and the front of the tender, restricting rearward vision. The 1921 Coal Miners’ strike meant that two class members (737 and 739) were converted to oil-burning. One of the modified locomotives subsequently caught fire at Salisbury shed, and both were reverted to coal firing by the end of the year. When the LSWR was amalgamated into the Southern Railway in 1923, Urie had done little to remedy the shortcomings of the N15s, and it fell to his successor to improve the class.

When Maunsell inherited the design as CME of the Southern Railway, he began trials using the weakest N15 (442) in 1924. The results indicated that better performance could be obtained by altering the steam circuit, valve travel and draughting arrangements, although the first two recommendations were deemed too costly for immediate implementation by the Locomotive Committee. Eight extra King Arthur-type boilers were ordered from North British and fitted to N15s 737–742 in 1925 in an effort to improve steaming. The remaining Urie boilers were fitted with standard Ross pop safety valves to ease maintenance. Maunsell also addressed draughting problems caused by the narrow Urie stovepipe chimney. The exhaust arrangements were modified on 737 using the King Arthur chimney design and reduced-diameter blastpipes. This proved successful, and all Urie N15s were modified over the period 1925–1929. The oil-burning equipment was refitted to 737 and 739 during the 1926 General Strike and removed in December of that year.

Beginning in 1928, all but 755 had their cylinder diameter reduced from 22 inches to 21 inches when renewals were due, improving speed on flat sections of railway, but affecting their performance on the gradients west of Salisbury.755 The Red Knight was modified in 1940 by Maunsell’s successor, Bulleid with his own design of 21 inch cylinders and streamlined steam passages. This was married to a Lemaître multiple-jet blastpipe and wide-diameter chimney, allowing the locomotive to produce performances akin to the more powerful Lord Nelson class. Four other N15s were so modified with four more on order, though the latter was cancelled due to wartime shortages of metal. The soft exhaust of the Lemaître multiple-jet blastpipe precipitated an adjustment to the smoke deflectors on three converted locomotives, with the tops angled to the vertical in an attempt to improve air-flow along the boiler cladding. This failed to achieve the desired effect, and the final two modified locomotives retained the Maunsell-style deflectors.

The final modifications to the Urie N15s involved the conversion of five locomotives (740, 745, 748, 749 and 752) to oil-firing in 1946–1947. This was in response to a government scheme to address a post-war coal shortage. The oil tanks were fabricated from welded steel and fitted within the tender coal space. After initial problems with 740 Merlin were rectified, the oil-fired locomotives proved good performers on Bournemouth services. A further addition to the oil-fired locomotives was electric headcode and cab lighting, which was retained when reverted to coal-firing in 1948.

The detail variations across the class meant the Urie N15s were placed into store over the winters of 1949 and 1952. The Maunsell King Arthur examples were easier to maintain, and the large number of modern Bulleid Pacific and British Railways Standard classes were able to undertake similar duties. The Urie N15s were brought into service during the summer months, although their deteriorating condition was demonstrated when 30754 The Green Knight was withdrawn with cracked frames in 1953. The slow running-down of the Urie N15s continued between 1955 and 1957, and several were stored prior to withdrawal. The last three were withdrawn from Basingstoke shed, with 30738 King Pellinore the final example to cease operation in 1958. All of engines were broken up for scrap, though their names were given to 20 BR Standard class 5 locomotives allocated to the Southern Region between 1959 and 1962.

The Maunsell King Arthur class also faced a decrease in suitable work on the Central and Eastern sections following the introduction of BR Standard class 5 and BR Standard class 4 4-6-0s in 1955. The gradual withdrawal of the Urie N15s, H15s and SR N15x classes presented an opportunity to replace the ageing Drummond watercart tenders fitted to 448–457 with Urie 5,000 imp gal bogie tenders. This coincided with a 1958 programme to similarly change the 3,500 imp gal Ashford tenders fitted to eight of the second batch Eastleigh Arthurs. The class remained intact until the completion of the Eastern section electrification when 17 were made redundant in 1959. More withdrawals took place in 1960 when an increase in Bulleid Pacifics allocated to the Western section reduced available work. The ranks thinned to 12 in 1961, and further withdrawals reduced the class to one, 30770 Sir Prianius. The class outlasted the newer – but less numerous – Lord Nelson class by one month when No. 30770 was withdrawn from Basingstoke Shed in November 1962.

When the SR was created in 1923, it immediately set about finding a solution to the problem that many of its inherited locomotives carried the same numbers. The first solution, was to prefix all locomotive numbers with a letter derived from the first letter of the main locomotive works on each section of the SR. New locomotives were then given a prefixed number in the appropriate series for the area in which they worked. Thus ex- London and South Western Railway were given a prefix of E for Eastleigh. Following nationalisation in 1948 numbering was initially a continuation of the Southern Railway system, though an S prefix was added to denote a pre-nationalisation locomotive. As each locomotive became due for overhaul and received its new livery, the numbering was changed to the British Railways standard numbering system, in the series 30448-30457 for the first ten and 30736-30755 and 30763-30806 for the rest

Number in Service.

Built Withdrawals No. in Service
BR Numbers Quantity
1918 30736-37



1919 30738-45



1922 30746-52



1923 30753-55



1925 30448-57






1926 30793-804



1927 30805-6





1953 30754






























  • The last locomotive of the class to be withdrawn from service was 30770 Sir Prianus in November 1962 whilst based at Basingstoke.
  • Of the 12 withdrawn in 1962 4 were based at Basingstoke (30765, 30770, 30793 and 30795), 3 were allocated to Salisbury (30451, 30796, and 30798), 3 at Eastleigh (30773, 30788 and 30804) and 2 at Bournemouth (30781 and 30782).
  • 30738 was withdrawn in 1958 and it was the last of the Urie locomotives.
  • 30754 was the first of the class to be withdrawn from service in January 1953.
  • 30763-92 were built in 1925 by the North British Locomotive Company in Glasgow.

Accidents and Incidents

  • On 26 November 1947, locomotive 753 King Arthur was hauling a passenger train that was in a rear-end collision with another at Farnborough, Hampshire due to a signalman’s error. Two people were killed.
  • On 22 January 1955, locomotive 30783 Sir Gillemere was in collision with H15 class 30485 at Eastleigh, Hampshire after its driver misread signals. The locomotive was subsequently repaired; The H15 was condemned.



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