R4823 HORNBY BR Mk1 BSO Brake Second Open E9428 crimson and cream

The Mark 1 coach was intended to be the standard carriage design for use across all of the British Railways’ lines on the network, incorporating the best features of the SR’s, GWR’s, LMS’s and LNER’s designs. It was also designed to be much stronger than previous coaching stock, to provide better protection for passengers in the event of an accident.

As a generalisation, Mk.1 coaches were built in two batches: the early vehicles (1951–60) and the 'Commonwealth' stock (from the type of bogie used) from 1961 onwards.

Designed by R.A Riddles (The Mechanical & Engineering Member of the Railway Executive) and aided by E. Pugson (Carriage & Wagon Chief Officer) and E.S Cox (Design Chief Officer), the Mark I carriage had a separate body and underframe, with a standard body length of 64ft 6in, an underframe 63ft 5in long and bogies at 46ft 6in centres. Body width was eventually settled at 8ft 8in, at cantrail height.

The stock was introduced in 1951, in sets, on 'Festival of Britain' trains being built through to 1964, when superseded by the Mark II design.