Alexander Armstrong has admitted the celebrity editions of Pointless are much more difficult to film than the normal episodes of the quiz show.
His comedy partner Ben Miller let slip, when the pair teamed up to talk about their new Spitfire ad, that the star-studded specials of the quiz took a long time to make.
Ben said: "I like your story that the celebrity shows are much more of a pain to film."
Alexander insisted: "They're never a pain - they're much longer.
"They're completely different to the regular shows. And I think celebrities are little bit on edge, because they're worried they're going to look stupid. I would be if I went on, you'd be terrified, because they've got much more to lose.
"And also they never shut up! They talk the whole way through. There comes a point where you do just have to say 'Shhhh'."
Ben added: "I know what you mean, because I was on one, and as a celebrity your attitude is very different because you want your moment in the limelight, so I can well see why they take longer to film."
And Alexander revealed they were hoping to get Dame Judi Dench and Harry Potter star Daniel Radcliffe to take part in the quiz show, but their agents aren't as keen as they are.
He said: "Any celebrities that fancy coming on, always good to have them.
"We get promises from people. Judi Dench has said that she'll come on - this was a message passed to us by her cousin. She said 'please, please ask me.'
"The trouble is we have to ask people through their agent and agents always say no.
"Daniel Radcliffe is very keen to come on, but we can only get to him through his gatekeepers."