DrFilth
I should explain how TV audiences work. A mate of mine owns an 'audience wrangling' company, and generally, even if you have a ticket, it doesn't mean that you will get in. Audience wrangling companies always distribute more tickets than there are seats available. If the studio holds (say) 250 people, 300 tickets, or more, will be sent out. They do this because a certain number of people won't show (tickets are free and people, so people are more inclined to go off and do something else if the mood takes them - as opposed to those to have paid £85 to see The Killers, for example).
What happens then, is that 280 people might turn up, but only the first 250 will actually get into the studio.
I've seen this dozens of times in shows that I've been too.
Some shows are more oversubscribed than others.
This episode of QT may well have been one of those.