A First Open or FO, is a type of railway carriage used by British Rail and subsequent operators since privatisation. They were first produced as British Railways Mark 1, and subsequently Mark 2, Mark 3, and Mark 4 variants were produced. This type of carriage is an "open coach" because of the arrangement of the seats inside – other types of carriage may be corridor based variants (FK) or have a brake compartment (BFO or BFK).

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Quick Facts British Rail First Open, In service ...

British Rail First Open
Mark 3 First Open coach at Marylebone in September 2008
In service	1951–
Manufacturer	Derby Litchurch Lane Works Doncaster Works Swindon Works Wolverton Works York Carriage Works Birmingham Railway Carriage & Wagon Company Metro-Cammell
Family name	British Railways Mark 1, Mark 2, Mark 3 and Mark 4
Constructed	Mk1 1951–1963 Mk2 1970-74 Mk3 1976-85 Mk4 1989-92
Fleet numbers	Mk1: 3000-3151 Mk2c: 3152-3169 Mk2d: 3170-3216 Mk2e: 3221-3275 Mk2f: 3276-3439 Mk3: 11000-11003/41003-41169 Mk3a: 11004-11063 Mk3b: 11064-11101 Mk4: 11200-11263
Capacity	Mk1: 42 Mk2c/d/e/f: Mk3/a/b: 48 Mk4: 46
Operators	British Rail InterCity ScotRail Abellio Greater Anglia Anglia Railways Arriva CrossCountry Cargo-D Chiltern Railways Direct Rail Services East Coast East Midlands Railway East Midlands Trains East Midlands Railway First Great Western FM Rail GNER Midland Mainline National Express East Anglia National Express East Coast London North Eastern Railway Riviera Trains Virgin CrossCountry Virgin Trains East Coast Virgin Trains West Coast West Coast Railways
Specifications
Car length	Mk1: 64 ft 6 in (19.66 m) Mk2/a: 65 ft 4 in (19.91 m) Mk2b/c/d/e/f: 66 ft 0 in (20.12 m) Mk3/a/b: 75 ft 0 in (22.86 m) Mk4: 23.4 m (76 ft 9+1⁄4 in)
Width	Mk1: 9 ft 3 in (2.82 m) Mk2/a:9 ft 3 in (2.82 m) Mk2bb/c/d/e/f: 66 ft 0 in (20.12 m) Mk3/a/b:75 ft 0 in (22.86 m) Mk4: 2.74 m (8 ft 11+7⁄8 in)
Height	Mk1 & Mk2: 12 ft 9+1⁄2 in (3.90 m)
Doors	Mk1 Manual slam doors, two on each side Mk2c/d/e/f Manual slam doors, two on each side Mk3/a/b Manual slam doors, two on each side (some modified to automatic plug doors) Mk4 Automatic plug doors, two on each side
Maximum speed	BR1/Cw: 90 mph (145 km/h) B4: 100 mph (161 km/h) BT10: 125 mph (201 km/h) SIG/BT41: 140 mph (225 km/h)
Weight	32.5 to 36.5 long tons (33.0 to 37.1 t; 36.4 to 40.9 short tons)
HVAC	Steam or electric heat, or both
Bogies	BR1, Commonwealth, B4, BT10 or SIG/BT41
Braking system(s)	Vacuum, air, or both
Coupling system	Drop-head knuckle coupler on draw-hook (dual)
Track gauge	4 ft 8+1⁄2 in (1,435 mm) standard gauge

Close

First Open carriages were introduced from 1951. The first three, for the London Midland Region, were the only Mk1 FO with no centre door, seating 42 in a 2+1 format. The second batch (3003–19), built from 1954, had a centre door in the centre seating bay, splitting the middle window into two thin panes. Carriages from 3020 had a separate centre vestibule with doors and reduced-width bays, still seating 42 in 2+1 format. BR1 type bogies were fitted as standard except on 3076–3080, a test batch built with Commonwealth bogies to improve ride quality. The ride quality of the BR1 bogie became poor after some use and, in 1961, changes were made. 3101–3151 were built with Commonwealth type bogies which became standard for a time, with the weight increasing by 5 tons. BR1 and Commonwealth bogies usually run at a maximum of 90 mph (140 km/h). Later, B4 bogies were fitted to further improve ride quality with a maximum of 100 mph (160 km/h). These carriages were fitted with Pullman gangways on standard 64 ft (20 m) frames and fitted with buck-eye couplers as standard. Buck-eye couplers can be dropped and buffers extended to allow use of screw coupling fitted locomotives. Vacuum brakes and steam heating were fitted as standard. A number of Mk1 FO were later fitted with air brakes in the late 1960s and 1970s, some retaining vacuum brakes and being dual braked.

The first Mk2 First Open were built to Mk2c design in 1970, followed by Mk2d from 1971 complete with air conditioning, with the ETH supply becoming standard along with a motor-alternator to provide the lighting, heating and air conditioning. The Mk2e was introduced in 1972–73 with introduction of fluorescent tubes for lighting with the major change being the more compact toilet. The final development was the Mk2f being introduced in 1973-75 which the interior design from the prototype Mk3s with improved seating and air conditioning through body side heaters. All the Mk2 veterans are fitted with B4 bogies with a maximum of 100 mph (160 km/h).

• Mk2d First Open 3231 named Apollo of Railfilms in Pullman livery with Golden Arrow & Fleche d'Or branding at Bristol Temple Meads in August 2012
• Mk2e First Open 3247 named Chatsworth of Venice-Simplon Orient Express' The Northern Belle in Pullman livery at Patchway in April 2012
• Mk2f First Open 3362 of West Coast Railways in unbranded InterCity Executive livery at Bristol Temple Meads in August 2009
• Mk2f First Open of FM Rail in Blue Pullman livery

First Mk3 prototypes were built at Derby Litchurch Lane Works in 1972 for the new Class 252 and were built to 75 ft 0 in (22.86 m) with BT5 bogies with a maximum of 125 mph (201 km/h). Production built Mark 3 stock for class 253 and 254 InterCity 125 were built at Derby Litchurch Lane in 1975–82 with BT10 bogies with a maximum of 125 mph (201 km/h) seat 48 and referred to as a trailer First. Mark 3a is the production built loco-hauled Mk3 built by BR at Derby Litchurch Lane introduced on the West Coast Main Line from 1975.

From 1979, seven First Open were used on the Glasgow to Edinburgh push pull service 11004–11010 with 11022 added later as 11004 was involved in the Polmont rail accident in 1984. ScotRail later down graded its First Open in 1986 to Open Composite were renumbered 119xx. Two First Open 11021 and 11032 were fitted with BT15 bogies along with 11058 fitted with BTS bogies in the mid-1980s.

With a further order for 38 Mk3b built at Derby Litchurch Lane in 1985 and were delivered new in InterCity livery with a number receiving names and being used on services on the West Coast Main Line offering a first class Pullman service.

• Mk3b First Open 11083 in BR blue grey livery at Marylebone in March 2009
• Mk3a First Open 11027 in original Virgin Trains West Coast livery at Birmingham New Street in July 2009
• Mk3a First Open 11019 in Direct Rail Services livery at London Victoria in December 2007
• Mk3b First Open in One livery at London Liverpool Street in March 2007
• Virgin Trains West Coast Mk3a First Open Interior in December 2009.
• Mk3a First Open in Virgin Trains Silver livery at London Euston in August 2009.
• Mk3b First Open 11091 in National Express East Anglia livery at London Liverpool Street on 8 March 2008, Peter Skuce
• Mk3b First Open 11092 in debranded One livery with National Express branding at Norwich in June 2008
• Mk3b First Open 11078 in debranded One livery with Greater Anglia branding at Stratford in August 2012

Built in 1991 and 1992 by Metro-Cammell as the main coaching stock for InterCity 225 sets, Mark 4 coaches were provided from-new with controlled-emission toilets and power-operated plug doors. They are fitted with Swiss-made SIG BT41A bogies and have a design maximum speed of 140 mph (225 km/h), though for operational reasons their normal maximum speed in service is 125 mph (201 km/h).