Maybe down to which show had most of its regular cast able to attend? Or which set was built etc.
Mock actually being improvised must have been interesting.
They did a clip show of Mock The Week in the end, because it was the last in the series anyway.
The other general point is that on 8 Out Of 10 Cats they could play all the other rounds (there were loads more in that first series) where they didn't talk about the news at all, so it was still possible to do a show of some kind, whereas obviously Mock The Week is rather constrained by talking about the week's news and not only had all the rest of the week's news been completely overshadowed, but it was not a funny story at all. So it would have been a very awkward episode, and probably they were better off just abandoning it and doing a clip show instead. Anne Robinson's crappy short-lived topical show What's The Problem was running at the time and they dropped that completely.
That said, back in September 2001 there was a short-lived panel show on C4 called This Week Only, which was presented by Joe Cornish with Lauren Laverne and Nick Frost as the regular panellists. It was a very low concept show, basically they'd just swap jokes about the week's news. Bizarrely they did an episode in the week of 9/11, and ignored it completely, which looked totally ridiculous, and just talked about silly sex surveys and stuff. On another forum a while back, one of the writers talked about that, they were writing the show when the news broke (and they said Nick Frost actually told them, which made it even more surreal), and with no real idea about what they could and couldn't do jokes about, they just carried on with writing all the stuff they were doing.
Actually there are probably loads of shows where there's been virtually nobody in the audience. Paul Merton talks in his autobiograhy about his first appearance on Wogan when virtually the entire audience was going to be made up of two coach parties, both of whom were stuck in traffic, so there was nobody there, and so his routine got no laughs at all (but he was told not to mention anything was wrong). I also remember Dave Pearce talking on Radio 1 about watching The Jack Docherty Show and realising halfway through there was no audience laughter - and no audience.
This thread has gone off the point a bit, sorry. BACK TO ROTAS.