LNER Class P1

The P1 class engines were initially equipped with two-cylinder booster engines attached to the trailing axle. They were engaged using a Westinghouse pump mounted on the boiler to engage the cylinder clutch.^[4] The booster engine had a tractive effort of 8,500 lbf (38 kN) when used, increasing the tractive effort of the locomotive from 38,500 to 47,000 lbf (171 to 209 kN). It was intended by Gresley that these boosters would be used to assist the locomotive while starting, and in topping the banks over which they travelled.

The tenders attached to the P1s had a specially designed dragbox to accommodate the booster equipment. In practice, the boosters were troublesome. When in operation, they filled the cab with steam, and the fireman's workload was doubled. The steam pipes from the boiler to the booster were prone to fracture, particularly on the sharp curves of the turning triangle at the New England shed. The boosters were removed from engines 2394 and 2393 in 1937 and 1938, respectively.^[5]

The two P1s were only ever used between New England and Ferme Park, the only route deemed suitable for them by the Operating Department. In practice there were issues with running such large trains with such powerful engines. The large three-cylinder engines required a considerable effort on the part of the fireman and the booster was known as particularly hungry for steam requiring even more coal. As a result, turns firing the P1s were considered as ones to avoid.^[6] It was also found that the heavier trains that the P1s could handle were too long for many of the passing loops resulting in delays to passenger trains.^[6] The result was that they were considered uneconomic as they were generally used in hauling trains of less than the 1,000 long tons (1,020 t; 1,120 short tons) for which they were built.^{[citation needed]} In 1934, No. 2394 was experimentally tried on the 07:45 am semi-fast passenger train from Kings Cross to Peterborough^[6] as part of the planning stage for P2 class locomotive 2001 Cock o' the North. Although the engine was able to reach a maximum speed of 65 mph (105 km/h), this put too much stress on the fireman who later commented that he was thankful not to have been going beyond Peterborough.^[7]

In 1942, both engines were overhauled and their original boilers, then in very poor condition, were replaced with A3-type 220 lbf/in² (1.52 MPa) boilers and their cylinder diameter was reduced to 19 inches (483 mm), leading to an increased tractive effort of 42,500 lbf (189 kN) The valve motion was retained in its original short-lap travel configuration. The rebuilding of no. 2394 took place in November 1942, after which it was intended to reclassify the locomotive P1/2. Before this reclassification could take place, no. 2393 was in the process of undergoing a similar rebuild, this being completed in January 1943, so the need to distinguish the two variants passed and both remained as Class P1.^[8]

Due to the reduction of heavy freight trains after the Second World War, both engines were withdrawn and scrapped by Edward Thompson in July 1945, the first Gresley locomotives to be withdrawn and scrapped by intention. The six-wheeled tenders were modified with standard dragboxes to run behind new Thompson Class B2 4-6-0s Nos 2815 Culford Hall and 1632 Belvoir Castle, while the boilers were removed and fitted to Gresley A1s No. 2557 Blair Atholl and 2565 Merry Hampton during their conversion from Class A1 to Class A3.^{[9] [10]}

• Boddy, M.G.; Brown, W.A.; Fry, E.V.; Hennigan, W.; Hoole, Ken; Manners, F.; Neve, E.; Platt, E.N.T.; Proud, P.; Yeadon, W.B. (March 1975). Locomotives of the L.N.E.R., part 2B: Tender Engines - Classes B1 to B19. Lincoln: RCTS. ISBN 0-901115-73-8. OCLC 655688865.
• Boddy, M. G.; Brown, W. A.; Neve, E.; Yeadon, W. B. (November 1983). Fry, E. V. (ed.). Locomotives of the L.N.E.R., Part 6B: Tender Engines—Classes O1 to P2. Kenilworth: RCTS. pp. 153–163. ISBN 0-901115-54-1.
• Cliffe, J.; Clay, J. F. (1973). The LNER's 2-6-2 and 2-8-2 Classes. Ian Allan.