| Great Western Railway 2900 Saint class | 
|---|
 | 
 | 
| Specifications | 
|---|
 Configuration:
  |  | 
|---|
 |  • Whyte | 4-6-0 (thirteen examples were built as 4-4-2 but rebuilt to 4-6-0 1912/13). | 
|---|
 |  • UIC | 2'Ch2 | 
|---|
 | Gauge | 4 ft 8+1⁄2 in (1,435 mm) standard gauge | 
|---|
 | Leading dia. | 3 ft 2 in (0.965 m) | 
|---|
 | Driver dia. | 6 ft 8+1⁄2 in (2.045 m) | 
|---|
 | Trailing dia. | 4 ft 1+1⁄2 in (1.257 m) (4-4-2 only) | 
|---|
 | Wheelbase | loco: 27 ft 1 in (8.26 m) –  27 ft 7 in (8.41 m) loco & tender:  53 ft 4+3⁄4 in (16.28 m) –  53 ft 10+3⁄4 in (16.43 m) | 
|---|
 | Length | 63 ft 0+1⁄4 in (19.21 m) | 
|---|
 | Width | 8 ft 11 in (2.718 m) | 
|---|
 | Height | 13 ft 3+1⁄2 in (4.051 m) | 
|---|
 | Axle load | 18 long tons (18 t; 20 short tons) | 
|---|
 | Loco weight | 68.30 long tons (69.40 t; 76.50 short tons) | 
|---|
 | Tender weight | 43.15 long tons (43.84 t; 48.33 short tons) | 
|---|
 | Fuel capacity | 5 long tons (5.1 t; 5.6 short tons) | 
|---|
 | Water cap. | 3,500 imp gal (16,000 L; 4,200 US gal) – 4,000 imp gal (18,000 L; 4,800 US gal) | 
|---|
 | Firebox: |  | 
|---|
 |  • Grate area | 27.22 sq ft (2.529 m2) | 
|---|
 | Boiler | GWR Standard No. 1 (with variations) | 
|---|
 | Boiler pressure | 225 psi (1.55 MPa) (production series) | 
|---|
 | Heating surface: |  | 
|---|
 |  • Firebox | 154.94 sq ft (14.394 m2) | 
|---|
 |  • Tubes and flues | 1,485.96 sq ft (138.050 m2) | 
|---|
 Superheater:
  |  | 
|---|
 |  • Type | "Swindon No. 3" | 
|---|
 |  • Heating area | 307.52 sq ft (28.570 m2) | 
|---|
 | Cylinders | Two, outside | 
|---|
 | Cylinder size | 18 in × 30 in (457 mm × 762 mm) or  18+1⁄2 in × 30 in (470 mm × 762 mm) | 
|---|
 | Valve gear | Stephenson | 
|---|
 | Valve type | 10 inches (254 mm) piston valves (2935 rebuilt with poppet valves) | 
|---|
 
  | 
| Performance figures | 
|---|
 | Tractive effort | 20,530 lbf (91.32 kN) – 24,395 lbf (108.51 kN) | 
|---|
 
  | 
| Career | 
|---|
 | Operators | Great Western Railway British Railways | 
|---|
 | Class | 2900 or Saint | 
|---|
 | Power class | GWR: C BR: 4P | 
|---|
 | Number in class | 76 | 
|---|
 | Numbers | 2900–2955, 2971-2990, 2998 | 
|---|
 | Axle load class | GWR: Red | 
|---|
 | Retired | 1924, 1931–1953 | 
|---|
 | Disposition | One rebuilt as Hall class (2925/4900 Saint Martin), remainder scrapped; One 4900 example has been backdated to 29XX specification | 
|---|
 
  | 
The Great Western Railway 2900 Class or Saint Class was built by the Great Western Railway's Swindon Works. The class incorporated several series of 2-cylinder steam locomotives designed by George Jackson Churchward and built between 1902 and 1913 with differences in dimensions for comparative purposes. The majority of these were built as 4-6-0 locomotives; but thirteen examples were built as 4-4-2 locomotives and later converted to 4-6-0 during 1912/13. They proved to be a highly successful class which established the design principles for GWR 2-cylinder classes over the next fifty years, and influenced similar classes on other British railways.