The Mark 2 family of railway carriages were British Rail

British Rail

British Railways , 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...

's second design of carriages. They were built by British Rail workshops (from 1969 British Rail Engineering Limited) between 1964 and 1975. They were of steel construction.
The Mark 2 has a semi-integral construction, giving it more strength than a Mark 1 in the event of an accident, although a key driver of the changed construction method was to overcome the serious corrosion problem point in the Mark 1 at the base of the body, where it was attached to the underframe.