The archive covers mainly the years between 1948 and 1953, during his employment with the London & North Eastern Railway (LNER) and the British Transport Commission (BTC). The collection includes reports spanning intermittent years; mainly between 1931 and 1973. Correspondence relating to the Modernisation Plan of 1955 and the London Plan, minutes, maps, memoranda and books are also included.

Much of the material relates to the London and North Eastern Railway company, the establishment of the British Transport Commission, the Railway Executive, the transformation of British Railways in the 1960s and the British Railways Board.

Bonavia held the position of Director of Studies for a brief time period and there are no records within the collection which relate to this post. Bonavia was concerned with the arrangement of the archive and has included a brief commentary on the items within the collection, which provides an insight into the matters with which he was involved.