| Power Classification | 6MT |
| Introduced | 1949 – 1950 |
| Designer | Peppercorn |
| Company | BR (LNER) |
| Weight – Loco | 66t 17cwt |
| Tender | 44t 4cwt |
| Driving Wheels | 5ft 2ins |
| Boiler Pressure | 225psi superheated |
| Cylinders | Outside – 20in x 26in |
| Tractive Effort | 32,080lbf |
| Valve Gear | Walschaert (piston valve) |
Thompson preferred a simple two cylinder design instead of Gresley’s three cylinder designs and rebuilt or planned to rebuild a number of locomotive types. The K4s were no exception, and the first outline drawing for a two cylinder rebuild appeared in February 1945, and incorporated a shortened B1 boiler. A rebuilding order for one locomotive was issued in March, and 3445 MacCailin Mor was rebuilt and returned to service in December 1945 and designated as a class K1 locomotive but this was subsequently amended to K1/1.
In January 1946, coal consumption trials were performed against a J39 by hauling coal trains between New England and Ferme Park. Neither engine was worked to capacity, but the K1/1 was deemed to have a greater reserve of power. The K1/1 was considered a good replacement for the J39 although its wheelbase was considered long for a 50ft turntable. The capacity of K1/1’s 3,500 gallon tender was recognised as a restriction, but a larger 4,300 gallon tender would have lengthened the locomotive further.
 |
K4 class introduced by Gresley in 1937 |
 |
K1/1 class which became the Ki prototype based on K4 rebuilt by Thompson in 1945 |
 |
K1 class introduced by Peppercorn in 1949 |
 |
J39 class introduced by Gresley in 1926 |
 |
K5 class of one engine which was a 1945 Thompson rebuild of a Gresley 1920 K3 class |
 |
O6 class MOS (WD) Stanier introduced in 1935 |
The double swing link pony truck on the original K4 was replaced with a spring side control pony truck as used on the K5 and the Stanier O6 2-8-0s. The cylinders were of a standard Thompson design as used on his B1 4-6-0s. The shortened boiler actually started life as a B1 Diagram 100A boiler that was cut down to become a prototype of the new Diagram 116 boiler. The original K4 cab was retained although the sides were altered to fit the new running plate.
An order for seventy production engines was placed in July 1947 with the North British Locomotive Co., although authority was only received in October 1947. The locomotives were built between 1949 and 1950, and incorporated a number of changes made by Peppercorn who was now the CME. The most visible change was that the running plate was cut away in front of the cylinders to improve access to the steam chests. The firebox was also fitted with a rocking grate and hopper ashpan, and the larger 4,200 gallon tenders were provided.
They were the last steam locomotives built to an LNER design although all were delivered under British Railways auspices. Numbered 62001–62070 they entered service between May 1949 and March 1950.
The K1s kept the double swing link pony truck, but the laminated bearing springs on these trucks were replaced with helical springs. This was due to problems seen on the laminated bearing springs used in the double swing link pony trucks then being fitted to the V2s. The K1/1 prototype kept its laminated bearing springs throughout its life.
Self cleaning apparatus was provided in the smokebox, but this proved detrimental to steaming. The North Eastern (NE) region K1s had their blastpipe tops reduced in diameter to 4.75in (from 5.125in) and reduced in height by 2in, to counteract this.
Number in Service.
| Built | Withdrawals | No. in Service | ||
| BR Numbers | Quantity | |||
| 1949 | 62001-62061 |
61 |
61 |
|
| 1950 | 62062-62070 |
9 |
70 |
|
| 1951-61 |
70 |
|||
| 1962 | 3 |
67 |
||
| 1963 |
7 |
60 |
||
| 1964 |
12 |
48 |
||
| 1965 |
17 |
31 |
||
| 1966 |
7 |
24 |
||
| 1967 |
24 |
0 |
||
The Peppercorn K1s proved to be useful and versatile engines. They worked extensively over ex-LNER territory but were chiefly associated with North East England and, following in the footsteps of their predecessors the K4s, the West Highland Line.
All were delivered to the Eastfield shed where they were run-in before being allocated further south. Many of the NE K1s would often be seen as far north as Edinburgh, and early on they were regularly used on the West Highland line. Later allocations were to the Eastern Region with a significant allocation to March.
Used throughout the former LNER network, the K1s proved to be very versatile and worked everything from the lighter coal trains through to express passenger services.
Ahead of withdrawals, the K1s started to move away from the GE (Great Eastern) Region in 1958, and by the end of 1961 only eight remained at March. These were moved to Doncaster and Retford by mid-1962, and withdrawals started a few months later. During the 1960s, the K1s tended to take over the work of withdrawn locomotives such as the colliery trains previously hauled by J26s, J27s, and J39s. Withdrawals continued throughout the 1960s, and the last K1 was withdrawn in 1967.
Like so many post-nationalisation classes the K1s had lamentably brief lives. All were withdrawn between 1962 and 1967, but the last to be retired managed to escape the cutter’s torch – but only just.
Locomotive allocations
|
Depot as of January |
1951 | 1955 | 1960 | 1964 | 1965 | 1966 |
1967 |
| Alnmouth | 7 | 7 |
6 |
||||
| Blaydon |
10 |
13 | 14 | ||||
| Consett | 2 |
1 |
|||||
| Darlington |
14 |
12 | 11 | 11 | 10 | 7 |
1 |
| Doncaster | 9 |
5 |
|||||
| Fort William | 5 |
5 |
|||||
| Frodingham | 5 |
4 |
|||||
| Gateshead | 2 |
2 |
|||||
| Haverton Hill |
7 |
||||||
| Heaton |
8 |
||||||
| Leeds Neville Hill | 1 | ||||||
| March |
30 |
25 |
18 |
||||
| Northallerton | 1 |
1 |
|||||
|
North Blyth |
1 | 1 | 5 |
12 |
|||
| Retford | 4 |
2 |
|||||
| South Blyth | 1 | 1 |
1 |
||||
| Stratford |
7 |
||||||
| Stockton on Tees |
8 |
6 |
|||||
| Sunderland |
2 |
||||||
| Thornaby |
3 |
||||||
| Tyne Dock |
3 |
||||||
| West Hartlepool | 1 | 1 |
4 |
||||
| York |
1 |
11 | 18 | 13 | 9 |
4 |
|
|
70 |
70 | 70 | 60 | 48 | 31 |
24 |
 |
62042 inside the shed at York that is now the National Railway Museum-February 1966. Having spents its entire working life based in the North Eastern Region 62042 was withdrawn from service at West Hartlepool in July 1967. |
 |
62007 at Sunderland-July 1966. Also based entirely in the North Eastern Region 62007 was withdrawn from service at Tyne Dock in September 1967. |
 |
62021 at Sunderland-July 1966. 62021 was based in the north east of England for its working like which ended in October 1966 at Tyne Dock |
 |
62004 at West Hartlepool-July 1966. 62004 spent 26 year based at Darlington before moving to West Hartlepool in December 1964. It remained in service at West Harlepool until December 1966 |
Preserved British Steam Locomotives 