Over the past three years, Richard Vranch has spun tales about everything from talking hippos and magic broccoli to a "who can be the nastiest?" competition between a horrid aunt and a bad wizard and a cow on a boat in the Mediterrean looking for pizza. Not that he can remember any of it.

"You're so in the moment when you're improvising you instantly forget what you've done," says the star of Whose Line Is It Anyway, Smack The Pony and Paul Merton's Improv Chums. "It's almost like a dream which just evaporates. People come up to you in the street and say, Hey, I saw you at the Comedy Store last night, that was a fantastic sketch where you were the parrot and Paul Merton was the orange', and you have absolutely no idea what they're on about."

Much to his chagrin, you're most likely to recognise Vranch from Channel 4's improvised comedy show Whose Line Is It Anyway?, on which he provided off-the-cuff piano accompaniment for the songs and hoedowns.

In many ways, he now says, this was "the worst job in the world": an actor and writer by trade, Vrance was denied the opportunity to take centre stage himself by a producer keen to keep him at the piano stool.

"Because of that people always associate me with the piano," he says. "I've got a very good ear and can make stuff up but I've never worked as a musician for a living."

In fact, the Comedy Store veteran is one of the most experienced improvisers around and The YarnBards, a show for everyone aged seven and over, is his attempt to do something new with the genre.

Co-founded with Lisa Rea, a director, performer and sometime member of the Ukulele Orchestra Of Great Britain (which explains the ukulele-based songs which often crop up in their shows), the group use audience suggestions to spin stories with no props or costumes to help them.

It's a format which goes back to the early days of Jackanory, when Vranch would improvise stories from viewer's suggestions alongside Sylvester McCoy.

"Someone will begin telling the story and then other people will pick up the narrative or come on and be the characters," explains Vranch. "Because there are only four of us, often the narrator has to get up and be in them as well. There's huge flexibility, mostly driven by practicalities like, hang on, we need another mouse over here!"

Today Vranch and Rea and Suki Webster will be joined by John Voce, while on May 26 the fourth YardBard will be Janice Phayre. As to how the often late-night art of improvisation translates for a family audience, Vranch says children's suggestions tend to be very different from adults' - and in a good way.

"If you ask someone to shout out anything they like in the dark, you get some very weird suggestions," he says. "At the Comedy Store, people shout out a lot of things to do with death and sex and toilets. With kids you get toilets but not so much death and sex. Kids are much better at suggestion because they still know how to play.

"So if you ask for a location, an adult might shout abattoir or bed or toilet, whereas a child might give you a magic castle on a cloud. As a starting point for a story, the children's suggestions are always more of a challenge - because you've got to match their imagination and then surprise them."

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