I went to the filming of one, done not too long before the 1997 elections
As you'll have guessed, the 'questions' made by the audience are all approved by the producers ahead of time (we were given little cards and handed them in, then the chosen few were called out just before it started so the cameras would know where to zoom in).
These questions were all the typical bland ones of the day - so if you had anything you wanted to say that didn't relate to the established news agenda, you'd either have to hope you could shoehorn it in as a randomly picked person at the end, or, if you are crazy, shout it out.
Not excusing dumbness or rudeness...But if you don't fit in with the BBC news narrative, you have no alternative.
Also saw the young Harriet Harman, and she was gorgeous.
(, Mon 12 Mar 2012, 8:00, Reply)