NINA Conti's In Your Face tour has been so successful that the Hampstead ventriloquist has added extra dates this autumn, among them the Grand Opera House in York on Monday.

After growing up in a theatrical family and studying philosophy at university, Conti took up ventriloquism at 27. "I was never very good at playing on my own, which is a bit of a downer for an only child. I always co-opted Mum or Dad into my playing. So I think when I started the ventriloquism thing, it was really me working out how to play on my own. Twenty years on," she says.

What she is doing now, says Conti, is "really just that": "Even with all the people on stage, I am basically talking to myself for two hours. I think I have finally worked out how to have fun for myself."

Her regular simian sidekick, Monk the deadpan monkey, makes an appearance as the show's MC, but on an unpredictable night of "the blind leading the blind", as Conti puts it, she builds each improvised performance around audience members being selected to wear cartoonish face masks.

Once on stage, Conti's chosen ones find that everything that comes out of their mouth is solely in her control, but this does not discomfit them. “I think they can tell I'm grateful to have them up there with me, and that I would never do anything mean or too outrageous when the mask is on," says Conti.

"What comes out is not them and it is not me; it is just… all stupid. I think it is noble to be really stupid. None of the comedy that happens makes a point or is full of clever observation; it just is."

When they locate their inner clown, with a little vocal help from Nina, the chosen ones do the most extraordinary things. "People are altered by hearing a different kind of voice coming out of their mouths," says Conti.

Occasionally, when liberating someone's inner entertainer, she has to consult her "moral compass". "Sometimes you get a bloke up on stage who gets...'all thrusty'," says Conti. "But the audience will always tell you what is OK. You can feel it. And if they get 'thrusty' to absolute silence, then they do not do it again."

What might the future hold for In Your Face? "I think this should be turned into a Jerry Springer type TV show," says Conti, not entirely seriously.

Nina Conti, In Your Face, Grand Opera House, York, Monday, November 6, 7.30pm. Box office: 0844 871 3024 or at