Technical Information


This class of 40 locomotives was introduced by the LMS in October 1933 to the first design of (later Sir) William A. Stanier. They were authorised at the meetings of Locomotive and Electrical Committee and Traffic Committee, both dated 27th July 1932, at a total estmated cost of £208,000. All were built at Crewe, the last, 13284, in March 1934.
The class was developed from the very successful George Hughes-designed ‘Horwich Crabs’ introduced in 1926, and many features from that class were carried over to William Stanier’s version, including the frame thickness of 1 1/16″, the narrow running plate angles, and the style of cab. They did though introduce all the features required by the new CME, including his triangular section wheel rims, GWR-derived axleboxes, taper boiler with Belpaire firebox incorporating large radius curved sides and roof, two-row superheater and smokebox regulator.

They were built in three batches: 13245-54, which had square-topped cylinders (except 13254); split taper boiler cladding, the front ring being parallel and the taper concentrated from the top feed rearwards; safety valves mounted in the top feed (in time, they would migrate to the firebox top), as with the GWR; and steam heating connections to the front of the loco as well as the tender. The second batch, 13255-64 had the safety valves on the firebox top; 13255-59 had the split taper boiler cladding, the remainder had a continuous taper (13245-59 would receive the continuous taper during the 1930s, except 13255, which retained the split type for life); and round topped cylinders. The third batch was 13265-84, which was similar to the second half of the previous batch, having all its characteristics. From 13275, though, the Midland-style ‘bell’ whistle was replaced by a Stanier hooter, while 13280-84 had only one mechanical lubricator plus a sight feed lubricator in the cab, in lieu of two mechanical lubricators fitted to all others.
Originally numbered 13245 to 13284, they were renumbered 2945 to 2984 from 1934, and 40000 was added to these on nationalisation to British Railways. They were always painted black, with red mixed traffic lining in LMS days; and grey / cream / red lining in the BR period. At some periods, particularly during the Second World War, they appeared in plain black without lining.

Throughout their LMS and BR careers, they were attached to the so-called ‘Fowler’ Standard 3,500 gallon tenders. Originally, these had snap head rivets and coal rails, although tender exchanges during service could see them run with other versions of the type, with countersunk rivets and / or without coal rails. Unlike other Stanier classes, they never ran with his 4,000 gallon type.

The drawing reproduced below, Diagram 1, is Euston Drawing No. E13, drawn by E. Stuart Cox and dated 24th April 1932. The major features of the Moguls are already apparent, but a major difference is that the boiler barrel is tapered along its full length; later Eric Langridge introduced the system allowing the same tapered section to be used for all Class 3 boilers by making the front ring parallel. A second variation is the vertical boiler backplate, which was sloped in production; and the dome cover appears to be about the same size as that eventually adopted for all domed boilers, but not for the Moguls.

Diagrams 2 and 3 show the final dimensions and ratios of the boiler after the fitting of a 1″ firebox tubeplate in place of the original 7/8″ item, so shortening the length between tubeplates by 1/8″. Diagram 4 gives details of the piston valves and valve events; and Diagram 5 is the weight diagram to ED181C in the Derby/Stanier system of numbering.

technical1 technical2  technical3


13245 under construction at Crewe works
Photo: Unknown
At various times, the power classification was:   4F, 5P4F, 5P5F, 6P5F and 5MT.
Boiler (Belpaire) Pressure 225 psi
160 x 2″ (later 202 x 13/4″)


Heating Surfaces (later)
Tubes, large and small
Superheater Flues 51/8″ O/D

14 elements (later 21)
Elements 11/4″O/D

1479 sq.ft.

155 sq.ft.
1634 sq.ft
232 sq.ft.
Grate Area 27.8 sq ft
Cylinders (two outside) 18″ bore
x 28″ stroke
Valve Gear Walscheart’s
Coupled Wheel Diameter 5’6″
Pony Truck Wheel Diameter  3’3½”
Nominal Tractive Effort  26,288 lb
Weight in working order

Weight (empty)
69 tons 2 cwt (engine) 42 tons 4 cwt (tender)
63 tons 5 cwt (engine) 21 tons 11 cwt (tender)
Height to Chimney 12′ 91/2″
Maximum Width 8’8″
Coal Capacity 5 tons
Water Capacity 3500 gallons
Building Cost
Engine £4,908
Tender £ 829


Allocations: 13268/2968/42968
Willesden 27/1/34 (New)
Edge Hill 20/4/35
Crewe 13/7/35 (North/South not specified)
Aston 14/12/35
Bescot 21/11/36
Birkenhead 12/6/37
Edge Hill  26/11/38
Willesden 10/5/41
Nuneaton 22/11/41
Crewe 21/2/42 (North/South not specified)
Crewe North 3/5/58
Birkenhead 10/6/61
Nuneaton 16/6/62
Mold Jct 22/6/63
Springs Branch 23/5/64
Gorton 15/5/65
Heaton Mersey 12/5/65
Springs Branch  8/1/66 to 31/12/66

Maintenance transferred to Swindon  1/12/63
Withdrawn 31/12/66

Tender Numbers
24/1/34 4537 (Fowler 3500 gallon type with snap head rivets)
12/94 SV3 (Stanier 4000 gallon welded type, ex-45110. LMS/BR number unknown)
4/98 4537
6/10 SV3 (Stanier 4000 gallon welded type, ex-45110. LMS/BR number unknown)
1/12 4537