| British Rail Brake Standard Open | |
|---|---|
 | |
| In service | 1955– |
| Manufacturer | Mark 1: BR Doncaster, Wolverton and Gloucester RCW Mark 2: BR Derby |
| Family name | British Railways Mark 1, British Rail Mark 2 |
| Constructed | Mark 1: 1955–1963 Mark 2: 1966–1974 |
| Number built | 340 |
| Fleet numbers | 9200–9539 |
| Capacity | Mark 1: 39 Mark 2/A–D: 31 Mark 2E/F: 32 |
| Operators | British Rail |
| Specifications | |
| Car length | 66 ft 0 in (20.12 m) |
| Width | 9 ft 3 in (2.82 m) |
| Height | 12 ft 9+1⁄2 in (3.90 m) |
| Maximum speed | 90–100 mph (145–161 km/h) |
| Weight | 33 long tons (34 t; 37 short tons) |
| HVAC | Steam, Electric or both |
| Bogies | BR1, Commonwealth, or B4 |
| Braking system(s) | Vacuum, Air, or both |
| Coupling system | Drop-head knuckle coupler on draw-hook |
| Track gauge | 4 ft 8+1⁄2 in (1,435 mm) standard gauge |
A Brake Standard Open or BSO, is a type of railway carriage used by British Rail. Both Mark 1 and Mark 2 types were built. Each consists of a standard class open passenger saloon with a centre aisle, a guard's compartment with hand brake and a lockable luggage compartment.
A number of Mark 1 and Mark 2 BSOs were converted to Brake Standard Open (Micro-Buffet) (BSOT), and fourteen Mark 2 BSOs were converted to Driving Brake Standard Open (DBSO). A number of BSO and BSOT coaches have been preserved, and some are still in use on main line charters. One significant survivor is No. 9267, the last surviving coach in the final excursion train on the Somerset & Dorset line on 6 March 1966, which is appropriately located at Midsomer Norton.[1]