What do you most enjoy about your nights of unplanned, off-the-cuff comedy with long-standing chums Lee Simpson, Suki Webster, Mike McShane and pianist Richard Vranch?

“I haven’t written a joke for 25 years! In Edinburgh one year, we were in a bar 20 minutes before the show was due to begin. We wanted to write down what impro games we would be doing in the show, but we realised we didn’t have a pen or paper. So we had to borrow the waiter’s pen and notepad. That’s the great thing about doing this show – there’s no stress involved whatsoever.”

What keeps these shows so fresh after 25 years?

“We don’t have any scripts or props. Planning doesn’t work because it throws the other performers, who don’t know what you’ve planned. It sounds very difficult and crazy to go on stage with nothing planned, but that’s actually the show’s strength. We’ve all worked together for a long time and know we can rely on each other.

“As a performer, you can never be bored because you’ve never heard it before and you’re doing something that five seconds ago you didn’t know you were going to do. To paraphrase Samuel Johnson, if you are bored of impro, you’re bored of life.”

What will keep this show running?

“It’s such a joy performing with the Chums. Our motto is: if it’s funny, it’s justified. That spirit of ‘anything can happen’ will continue. With good health, we can carry on for years. With this show, there’s no inbuilt obsolescence – apart from our own inbuilt obsolescence.” A few tickets remain for Paul Merton’s Impro Chums.

• Tomorrow’s show leads off a burst of heavyweight comedy at the Grand Opera House, York, where grumpy Scot Frankie Boyle and grouchy Englishman Jimmy Carr will compete for most offensive joke of the week ahead.

A smattering of seats are still on sale for Carr’s latest York instalment of his Rapier Wit tour on Tuesday at 8pm, while tickets sold out as ludicrously long ago as last August for Boyle’s two nights of I Would Happily Punch Every One Of You In The Face. Will his headline-making Down’s Syndrome material still feature? Find out on Wednesday and Thursday.

All four nights start at 8pm. Box office: 0844 847 2322.