More than 10 years ago Cecil J. Allen wrote two small books, one dealing with the Stanier Pacifics of the L.M.S.R and the other with the Gresley Pacifics of the L.N.E.R, and also, in conjunction with S.C. Townroe, a book on the Bulleid Pacifics of the S.R., all long since out of print. Much happened after that; in particular the development of the Gresley Pacific designs under Thomson and Peppercorn; the rebuilding of the Bulleid Pacifics; and, of course, the evolution of standard Pacific designs of British Railways.