"This book contains details of preserved standard (4' 8 1/2") and broad (7' 0 1/4") gauge locomotives and multiple unit vehicles which have been in the ownership of, built to the designs of, or operated under the jurisdiction of, the British Railways Board, its constituents or its descendants, in revenue earning service or on the "main line". Locomotives solely used in workshops and depots are excluded as are those solely built for export. Only vehicles no longer in the ownership of the descendants of the British Railways Board or the commercial railway companies are included."--Page 4.