British Railways (BR), which from 1965 traded as British Rail, was the operator of most of the rail transport in Great Britain between 1948 and 1997. It was formed from the nationalisation of the “Big Four” British railway companies and lasted until the gradual privatisation of British Rail, in stages between 1994 and 1997. Originally a trading brand of the Railway Executive of the British Transport Commission, it became an independent statutory corporation in 1962: the British Railways Board.

Info gleaned from Wikipedia