Not D18 as it appears to be, as the headcode box is incorrect.

David J. Hayes says "The picture is dated a Saturday and the details for 1S31 in the May 1969-May 1970 WTT show it running as the 19:19 MWSO Motorail from Newhaven Harbour to Stirling. This ran during the period 19th May to 27th September 1969 and was booked to call at Kensington Olympia (20:51-21:00). Interestingly, it didn't join the WCML at Willesden, but ran instead via Old Oak Common."

He adds "Further to my initial comment, it appears the service was booked northwards from London via the Midland main Line, which was reached from Kensington Olympia by way of Old Oak East Junction-Park Royal-South Greenford-West Ealing-Acton Main Line-Acton Wells Junction and Brent Curve Junction."