I suspect it is in fact not Exmouth Junction, but Exeter (St David's) - 83C. The clue is the coal wagons behind 30951 which are on a incline which led to the coaling stage at St David's. Following the Western Region take over some engines were stored in the down sidings at Exmouth Junction and others went to St David's loco for storage. Another storage location was a siding beside the head shut for the C & W Depot. Exmouth Junction did not have an incline whereby the track was much higher than ground level.
This is also confirmed by Richard Parkinson's excellent book, 'Exeter Memories - Exmouth Junction Fireman'. On page 23 is a photograph of 30951 in store at St David's with Class 700 30700, N 31409, and two further Class 700's 30689 and 30697. The photograph is dated December 1962. Again I would question the date (unless it was very early in December) as on 3rd January 1963 30689 and 30697 were on snow plough duties and were stranded at Sourton Cross in deep snow and I think cylinder damage lead to them being condemned. A couple of months later Exmouth Junction received two Q 0-6-0 engines for snow plough duties (30530/30531) and these were replaced later by WR 0-6-0's of the 2251 Class. One of which was 3205 now resident on the SDR.
Many thanks for this David - I bow to your detailed local knowledge.