Someone was mentoning about the GMTV airtime being used for Formula one, and how GMTV would get ITV airtime back in return. They also questioned whether TV-am would've been so co-operative.
Well, I'm sure there was an occasion when the Scotland football team were playing a match, that was in the early morning for us. And as it was being played during TV-am airtime, apparently Channel 4 showed the match on STV's behalf. Now, I'm not saying it was a case of TV-am saying no, but I think that there would've been an IBA ruling that STV couldn't broadcast the match during TV-am airtime.
This was in October 1985 when they played a World Cup qualifier against Australia which kicked off at 8.30am, and as you say, it was broadcast on Channel 4 rather than ITV (it presumably would have been networked if ITV had shown it, it was a play-off). But those were the days when C4 was very much ITV2, and maybe they would always have shown it there because they thought TVam was more important, much like how the Beeb would show matches on BBC2 to avoid moving the news.
1988 telethon and TV-am was answered here:
https://tvforum.uk/forums/post646942#post-646942
With regards to Thames, their trailer for their 1985 marathon is here, but no idea what happened to TV-am that day in London (could it have been shifted to Channel 4 for one morning in one region?)
I think that "24 hours" suggestion is just a figure of speech and while it was on air for 24 hours, it wasn't continuously. The first Thames Telethon in 1980 certainly wasn't continuous because they had to go off for schools programmes, which I think was also the case here.
The other interesting thing about that 1985 Thames Telethon is that as they were doing their own thing, they sent the final part of a mini-series to Central to allow them to play it out to all the other regions (and they showed it some other night). Unfortunately somewhere along the way to Central they lost one of the reels and it ended twenty minutes early.
As I mentioned, heavens, eight years ago, in 1988 TVam had nothing at all to do with the Telethon because the unions said they'd boycott the whole thing if they were allowed to take part during the strike. I don't know if that meant they still switched to TV-am and they sold the adverts within that part of the show, or the various regions just carried on, but they didn't make anything for it. In 1992 they did contribute, they had an hour between 6.30 and 7.30 which was a "special" edition of Michaela Strachan's usual show which just linked cartoons together. I assume that was just treated as another contribution to the show like all the other bits, as mentioned in 1992 the main kids' bit was The Disney Club (which I'm pretty sure was pre-recorded) and that came from STV. Indeed I can remember they still had the local number on the screen during the Michaela bit so presumably it was still being broadcast from the regions rather than TV-am.