LNER Class P1

Infobox Locomotive
name = LNER Class P1
powertype = steam
designer = Sir Nigel Gresley
builder = London & North Eastern Railway
builddate = June & November 1925
totalproduction = 2
whytetype = 2-8-2
gauge = 1435 mm (4 ft 8½ in)
leadingsize = convert|3|ft|2|in|m|abbr=on
driversize = convert|5|ft|2|in|m|abbr=on
trailingsize = convert|3|ft|8|in|m|abbr=on
wheelbase = convert|36|ft|2|in|m|abbr=on
axleload = 18 tons 13 cwt (18.9 t)
locotenderweight = 100 long tons
consumption = unknown, but high
boiler = convert|6|ft|5|in|m|abbr=on max.
boilerpressure = 180 psi (1.24 MPa
firearea = convert|41.25|sqft|m2|abbr=on
tubearea = 1880 sq ft (168×2.25 in)
fluearea = 835 sq ft (32×5.25 in)
fireboxarea = convert|215|sqft|m2|abbr=on
totalsurface = convert|3455|sqft|m2|abbr=on
superheatertype = Robinson
valvegear = Walschaerts & Gresley, with steam reversing gear
cylindercount = 3, with 2 more in a booster unit
cylindersize = 20 in x 26 in (10 in×12 in in booster)
tractiveeffort = (85% boiler pressure) 38,500 lbf (171 kN)|

The London and North Eastern Railway Class P1 Mineral 2-8-2 Mikado was a class of 2 steam locomotives designed Nigel Gresley. They were some of the most powerful freight locotives ever designed in Britain, and it was initially intended they be a more powerful 2-10-0 version of the earlier Class O2 2-8-0s. The design was submitted in August 1923, for use between Peterborough and London, and also between Immingham and Wath Yard. The power was quoted as being 25% more than the O2.

There were two locomotives built: No. 2393 was completed in June 1925, whilst No. 2394 was completed in November. They differed in the main by having different superheaters fitted. There were four others planned to replace older 0-8-0 locomotives, but these were never built. They were initially put to work between New England and Ferme Park yards, which was the only route deemed suitable for them, however they were only economically viable when hauling heavier trains of 1000 tons or more, loads which were comparatively rare on Britain's railways at that time. The locomotives were finally withdrawn in July 1945, and the boilers used to rebuild Class A1 Nos. 2557 and 2565 to Class A3, and the tenders modified and used on Thompson Class B2 locomotives, so neither survived into preservation.