SR N15 4-6-0 No 30785 Sir Mador de la Porte down express passing Winchfield on 20 April 1949. 30785 received BR renumbering in August 1948, and had its snifting valves removed whilst shopped during Jan/Feb 1949, and received a full BR livery repaint in May 1951. This could be the 11.30 Waterloo – Bournemouth West, The duty number of which is I believe Nine Elms duty 122 (photo not quite sharp enough to be certain).Looking at the carriage workings for winter 1947 the 11.30 then had a 6 dining set leading, just like in this photo.

Photo: E.C. Griffith / Rail Archive Stephenson