This is on the LCDR main line between St Mary Cray and St Mary Cray Junc. This is a down boat train from Victoria to Dover via Chatham.
Given the date this was a bit unusual at this time as this line had been electrified throughout via Chatham since June 1959 and Dover boat trains by this route were usually 4CEP/4BEP/4CEP/MLV EMUs although the odd steam working was not unknown.