BR Standard Class 7

British Railways Standard Class 7 Britannia Class
Standard Class 7 Oliver Cromwell at Carlisle Kingmoor in 1968
Type and origin Power type Steam Designer Robert Riddles Builder BR Crewe Works Build date January 1951 – September 1954 Total produced 55
Specifications Configuration: ​  • Whyte 4-6-2  • UIC 2′C1′h2 Gauge 4 ft 8+1⁄2 in (1,435 mm) standard gauge Leading dia. 3 ft 0 in (0.914 m) Driver dia. 6 ft 2 in (1.880 m) Trailing dia. 3 ft 3+1⁄2 in (1.003 m) Length 68 ft 9 in (20.96 m) Width 8 ft 8+3⁄4 in (2.66 m) Height 13 ft 0+1⁄2 in (3.98 m)7004 Axle load 20.5 long tons (20.8 t; 23.0 short tons) Adhesive weight 61.5 long tons (62.5 t; 68.9 short tons) Loco weight 94 long tons (96 t; 105 short tons) Tender weight BR1: 49.15 long tons (49.94 t; 55.05 short tons) BR1A: 52.5 long tons (53.3 t; 58.8 short tons) BR1D: 54.5 long tons (55.4 t; 61.0 short tons) Tender type BR1 (40), BR1A (5), or BR1D (10) Fuel type Coal Fuel capacity BR1/BR1A: 7.0 long tons (7.1 t; 7.8 short tons) BR1D: 9.0 long tons (9.1 t; 10.1 short tons) Water cap. BR1 4,250 imp gal (19,300 L; 5,100 US gal) BR1A: 5,000 imp gal (23,000 L; 6,000 US gal) BR1D: 4,750 imp gal (21,600 L; 5,700 US gal) Firebox: ​  • Grate area 42 sq ft (3.9 m2) Boiler BR1 Boiler pressure 250 psi (1.72 MPa) Heating surface: ​  • Firebox 210 sq ft (20 m2)  • Tubes and flues 2,264 sq ft (210.3 m2) Superheater: ​  • Heating area 718 sq ft (66.7 m2) Cylinders Two, outside Cylinder size 20 in × 28 in (508 mm × 711 mm)
Performance figures Tractive effort 32,150 lbf (143.0 kN) Factor of adh. 4.23
Career Operators British Railways Power class 7MT Numbers 70000–70054 Nicknames Brits Axle load class Route availability 8 BR (WR): Red Locale Eastern Region, London Midland Region, Scottish Region, Southern Region, Western Region Withdrawn June 1965 – August 1968 Disposition Two preserved, remainder scrapped

The BR Standard Class 7,^[1] otherwise known as the Britannia Class, is a class of 4-6-2 Pacific steam locomotive designed under Robert Riddles for use by British Railways for mixed-traffic duties. 55 were constructed between 1951 and 1954. The design employed results from the 1948 locomotive exchanges undertaken in advance of further locomotive classes being constructed. Three batches were constructed at Crewe Works, before the publication of the 1955 Modernisation Plan.

The Britannia Class design was based on best practice from the pre-nationalisation railway companies in terms of operating efficiency and lower maintenance costs;^[2] various weight-saving measures also increased the route availability of a Pacific-type locomotive on the British Railways network.^[3] The Britannias received a positive reception from their crews, with those regularly operating the locomotives giving them favourable reports as regards performance.^[4] However, operation in some areas of the British Railway network returned negative feedback, primarily due to indifferent operation of the locomotive, with its effects on adhering to timetables. They were capable of reaching speeds of up to 90 mph (145 km/h).^[5]

The Britannias took their names from great Britons, former Star class locomotives, and Scottish firths.^[4] The class remained in service until the last was withdrawn in 1968. Two survived into preservation, the first-of-class, number 70000 Britannia, and 70013 Oliver Cromwell. Number 70000 has hauled mainline excursions and 70013, after a period of display following limited steaming, returned to mainline steam in 2008 for the first time since leaving British Railways ownership. 70000 was returned to the main line in 2011.