Thanks to John Atkinson for once again getting the gen on this. This is 2HAP 6045 in the wall sidings at Brighton. Formed of coaches S61243 and S75363. The unit was repainted blue/grey in April 1982 and became half of 4CAP 3310 in May 1983 which pins the date down nicely. The slide is dated March 1987 which must be an error, Photographer unknown.