i) births and deaths

2 August 1990: death of Edwin Richfield, who played Captain John Hart in The Sea Devils (Third Doctor, 1972) – not the Captain John Hart of later Torchwood! – and also Mestor in The Twin Dilemma (Sixth Doctor, 1984). I think it's reasonably clear which part required more make-up…

2 August 1992: birth of Greg Austin, who played Charlie in Class (2016). Again, to avoid confusion, he is not the same person as my former colleague Greg Austin.

2 August 2016: death of Terence Bayler, who played Yendom, a doomed human slave, in The Ark (First Doctor, 1966) and mesmerised soldier Major Barrington in The War Games (Second Doctor, 1969).

ii) webcast anniversary

2nd August 2002: release of the first episode of Real Time on the BBC website. The Sixth Doctor and Evelyn Smythe land on a deserted planet to investigate rumours of Cybermen. One of the scientists who they encounter there closely resembles Chang Lee from The Movie because they are both played by Yee Jee Tso.

iii) date specified in-universe

From Lloyd Rose's 2004 Seventh Doctor novel The Algebra of Ice, year unspecified:

 ‘Now, what was that other information you wanted? Oh yes.’ He picked up another file. ‘ “U” working on entropy. That must have been Pat Unwin. Not a strong character, our Pat.’
   ‘Where did he study?’
   ‘Warwick. Should have warned us. Still, a triple first at Oxford. He was a damn fine mathematician and we’d have kept him on if he hadn’t gone alcoholic on us.’
   ‘I understand you’re generally tolerant of. . . that sort of thing.’
   ‘Within reason. Very high-strung a lot of these chaps. Have to make allowances. But as soon as they become unusual, we ship them off to a doctor or a rest home with an AA program. Unwin wasn’t having any of that. Took to reeling through the halls muttering. All right. Not the first one. We could deal with that. But when he started sneaking into people’s offices and erasing their files it was a bit much. When we called him on it, he began ranting about how useless the work here was and how his ideas were going to change the world. We got in the lads in the white coats pronto, I can tell you.’
   The Doctor nodded sympathetically. ‘So he did go to a “rest home”.’
   ‘Should have thrown him in an institution. Drying-out place we have near Dover; he just walked away. We’ve been searching for him ever since. The things he has in his head. Classified, you know. Don’t want them showing up in the hands of people who aren’t our friends. Though for all I know, he might write them on the wall of a toilet, or publish them on that cyber place, space, what’s it called?’
   ‘The Internet.’
   ‘That’s it.’
   ‘But so far he doesn’t seem to have said anything. Exactly how long ago was this?’
   ‘Hasn’t been seen since 2 August.’