The Black Redstart was still present this morning. Better photos show a pale secondary wing panel which presumably indicates a first-winter male. Will have a read up when back in the office.
Update 130121: The secondary panel can be shown by females and first-winter males and according to HWPB ageing also needs to consider advanced males 'paradoxus' and retarded males 'cairii'. This bird doesn't appear to be an advanced male, its rather uniform and an advanced bird would presumably show darker feather tracts. So either a non-advanced first-winter male or a female. I couldn't make out any moult contrast in the greater coverts and from what I can see from the photos the rectrices do look quite broad (not pointed like expected in first-winter) which could indicate an adult which would make it a female.
Update 200121: Just re-visited this bird at Beddington HERE- check out the contrast in the coverts with black greater coverts indicating a first-winter male for that one.