| Introduced | 1932 |
| Designer | G T Glover |
| Company | Great Norther Railway |
| Weight | Engine – 65t 1cwt Tender – 38t 10cwt |
| Driving Wheels | 6ft 7ins |
| Boiler Pressure | 215psi superheated (Later reduced to 200psi) |
| Cylinders | One inside high pressure cylinder – 17¼in x 26in – and two Outside low pressure cylinders – 19in x 26in |
| Tractive Effort | 20,435lbf (Later reduced to 19,000lbf) |
| Valve Gear | Stephenson |
The locomotive was built to haul express passenger trains over the 112 miles between Dublin and Belfast for the Great Northern Railway (GNR). This railway straddled the border of Irish Republic and Northern Ireland following the creation of Northern Ireland in 1921when Ireland was partitioned into Northern Ireland and Southern Ireland. The Great Northern Railway was thus not incorporated into the Córas Iompair Éireann (CIÉ) or the Ulster Transport Authority (UTA). As a result of mounting losses the Great Northern Railway was run jointly by the CIÉ and UTA with an independent board from 1953 until 1958 when it was dissolved and its remaining stock split equally between the two parties.
The locomotive was one of five V class engines built by Beyer Peacock & Co in Manchester in 1932 as works number 6733 but the tender was built at the GNR workshops at Dundalk. It was given the number 85 by the GNR and the name Merlin – All of the locomotives in the V class were named after birds.
The designer, George T Glover had become Chief Locomotive Designer for the Great Northern Railway in 1912 after having worked for the North Eastern Railway in England. The V class locomotives he designed were compounds.
While the design for the V class was being prepared, the GNR sent men over to the LMS to experience and learn from the compounds in use in Britain at the time. The main dimensions of the LMS design (one of which, No.1000, is preserved at York) included 6ft 9in driving wheels, a 19in x 26in high-pressure cylinder and two 21in x 26in low-pressure cylinders. The working pressure was 220 psi with a tractive effort of 22,649lb. However, the Great Northern design ultimately had 6ft 7in driving wheels a 17¼ in x 26in high-pressure cylinder, 19in x 26in low-pressure cylinders and 250 psi working pressure, which produced a tractive effort of 23,762 lb. Interestingly, both designs had the coupling rods outside the connecting rods. The V class compounds cost £5,847 each.
 | Midland Railway compound introduced by Johnson in 1902 and rebuilt by Deeley in 1914 |
| | Great Northern Railway V class introduced in 1932 |
In 1947 the V class locomotives were selected to haul the new Enterprise non-stop service between Dublin and Belfast. This premium service was limited to a load of seven bogie coaches and reduced the time between the two cities by 22 minutes. The tight schedule resulted in severe maintenance problems including – hot boxes, problems with connecting rods and even, soon, boilers needing a re-tube. As a result, the boiler working pressure was reduced to 200 psi, which brought the tractive effort down to just over 19,000lb.
In 1957 the locomotives were replaced by diesel multiple units and they were relegated to other duties.
When the GNR was split in 1958 85 was one of two locomotives allocated to the CIÉ.
Merlin had spent its final years as a spare at Dundalk works and was called on occasionally to haul trains to Dublin.
The CIÉ withdrew all steam traction in 1963 by which time it was the last of the class still in service. The other CIÉ engine had been withdrawn from service in 1959 and the three UTA locomotives in 1960 and 1961. In 1963 the locomotive was inspected by the ULA who were considering buying it but bought Vs class 207 Boyne instead. The rejected Merlin moved to Dublin (Amiens Street) and then to the city’s Inchicore Works for scrapping.
At the time the Witham Street Transport Museum in Belfast had plans to acquire the last of the compounds and in the end a purchase was agreed, with the locomotive (minus its tender) costing £600. Buffers and drawgear were fitted to the cab end of the engine and the 4-4-0 was moved from Inchicore to Amiens Street in April 1965, then to Dundalk the following month. It remained there for more than a year before mowing to Belfast’s Adelaide shed. When Adelaide closed, No.85 moved to the goods store in Lisburn and it wasn’t until late 1969, four years after purchase, that the locomotive finally arrived at the museum in Witham Street.
It was displayed in the museum until 1976 when it was moved to Harland and Wolff shipyard for a comprehensive overhaul which was organised by the Museum, the Railway Preservation Society of Ireland (RPSI) and Lord Dunleath. Following completion of the overhaul the locomotive was moved to the RPSI’s Whitehead headquarters in County Antrim. At Whitehead the locomotive was paired with aformer Vs class 4,000 gallon tender which it ran with for a couple of years until a smaller 3,000 gallon tender was fitted.
After a series of running-in trips in 1985 and 1986 the locomotive was officially launched into traffic in June 1986 by Lord Dunleath. In September 1986 the locomotive hauled the eight coach official Belfast – Dublin Enterprise. In August 1987 the locomotive hauled the 40th anniversary Enterprise train and completed the journey from Belfast to Dublin in a minute less than the 1947 schedule for the train.
Since 1986 the locomotive has been used by the RPSI on tours all over Ireland. Following the placing of 41000 on static display Merlin is the last working full sized compound locomotive working in the British Isles.
In 2004 the boiler certificate expired and the locomotive went on static display until August 2009 when it was decided to investigate steaming it again. After major work the locomotive returned to traffic in August 2014.
In March 2022 the locomotive operated on the main line which was the first steam locomotive to do so in the Republic of Ireland for two years.
The engine remains owned by the Ulster Folk and Transport Museum whilst the tender is owned by the Railway Preservation Society of Ireland.
The boiler ticket will expire in 2024.
Preserved British Steam Locomotives 