SR Battle of Britain 4-6-2 No 34077 603 Squadron a Down express passes the Kentish hopfields near Tudeley on 26 February 1960.
The headcode says it is a Charing X or Cannon St Ramsgate/Margate via Orpington and Dover however the coaching stock comprises a relief Victoria - Folkestone or Dover boat train set. Could be a boat train which most unusally started from London Bridge - this was not entirely unknown in an emergency I believe.

Photo: D.M.C. Hepburne-Scott / Rail Archive Stephenson