Photos by Ben Peissel, no reproduction without permission.
These photos show an episode of Dr Who being dubbed at Pebble Mill. The Doctor in question is Peter Davison, who was the fifth Doctor, and played the role between 1982-4.
Andy Freeth is one of the dubbing mixers shown.
The episode is part 1 of ‘Resurrection of the Daleks’. This was shown as 2 double-length episodes rather than the usual four 25 minute ones, due to the scheduling around the 1984 Olympics. Perhaps all the dubbing facilities in London were busy with the Olympics, where Dr Who would normally have been dubbed, meaning that it came to Pebble Mill instead.
I understand that only one full episode of Dr Who was recorded in Studio A, in 1977, the Horror of Fang Rock, but that would be earlier than these photos.