This frosty scene is making me scratch my head a bit. 33056 ' The Burmah Star' with a passenger train headcode 99. This can be either a Brighton to Bristol/Cardiff or London Bridge to Uckfield working. The SR concrete lamposts and footbridge suggest Oxted line rather than between Cosham and Southampton. After a long trawl through photos of various stations I can confirm that this is an up service at Buxted but the only loco hauled service from Uckfield was in the evening. The shadows make this a morning shot. the second vehicle is a Mk2 TSO or BSO which the Southern did not have.
Awaiting confirmation that this a scratch WR set standing in due to a shortage of DEMU's.
Image undated but 33056 was named September 1980, so post then and it gained the all over grey roof after 1981.
Info from http://www.derbysulzers.com/class33b.html states that the 0711 Uckfield to London Bridge service reverted to loco haulage during Jan and Feb 1986. Looks just a bit too light to be then?
Photographer unknown.