Tourist Second Open or Tourist Standard Open, abbreviated to TSO, is a type of British Railways coach. The designation "Tourist" was originally as opposed to a normal SO coach. Both types have the same number of seating bays per coach, but the TSO has four seats across, arranged 2+2 either side of a central aisle, while an SO has 3 seats across, arranged 2+1 with an offset aisle. Both offer the same legroom, but there is slightly less width per passenger in a TSO.
Mark 2A TSO 5278 "Melisande" at Cheltenham Spa in September 2004
Interior of a Mark 1 TSO, Avon Valley Railway
Arriva Trains Northern Mark 2F TSO 6035 at Carlisle on 27 August 2004
Interior detail of a Mark 2b TSO
British Rail Mark 1 is the family designation for the first standardised designs of railway carriages built by British Railways (BR) from 1951 until 1974, now used only for charter services on the main lines or on preserved railways.
Mark 1 Open First on Commonwealth bogies at Tyne Yard in March 2009
Interior of a Mark 1 SO (Second Open) Colne Valley Railway
Mark 1 Brake Suburban E43190 at the Buckinghamshire Railway Centre This type was shorter than standard and has no corridor
Mark 1 coach fitted with a British-style dual buffer-and-chain/janney coupler with knuckle swung out of the way
