Jon Culshaw: A very good impression of a man who wants to outdo Rory Bremner

The IoS interview: Jon Culshaw, satirist

Jon Culshaw knew he had arrived as an impressionist when his William Hague fooled the switchboard at 10 Downing Street. It was a Wednesday morning in January 1998 and, having just perfected his Hague voice, he decided to give it the ultimate test-drive on his live hoax-call slot on Capital Radio. As luck would have it, Tony Blair was in and agreed to take the call.

"He played along very good-naturedly," remembers Culshaw, slipping into his Blair voice briefly. "He found me out immediately, because although this was at the height of the 'Call me Tony' period, Hague persisted in calling him Prime Minister. So when I said 'Hello Tony' he knew it couldn't be the Leader of the Opposition. I offered to make him a present of some item that Ffion and I had found at a car boot sale, and he came back: 'You could hand it over at Prime Minister's Questions. We might have a better exchange than usual.' After that someone at No 10 pulled the plug on it. But I heard later that Blair was rather peeved about that. I think the call had made his day."

And that says as much about Jon Culshaw as it does about the PM. Now 34, he has been fooling people with spoof calls and famous voices for most of his career, all the way from local radio in Lancashire to the multi-award-winning Dead Ringers on Radio 4, which last week became the latest radio comedy to make the big step up to BBC2. His style is gentle, his aim mischievous fun. He will admit to a taste for Victor Lewis-Smith – what you might call the hardcore end of the comedy hoax genre – "but my calls have always been benign. I don't delight in embarrassing people".

What Culshaw considers a successful call on Dead Ringers – the show about to enter its eighth series – is one that prompts mild bewilderment at the other end: the woman at directory enquiries approached by Doctor Who trying to track down The Master, or Obi-Wan Kenobi checking that his hotel room will be well-lit ("the last one was a little on the dark side"). It's harmless, satirical fun – which is exactly the mood that Culshaw hopes to carry over into television when Dead Ringers makes its first appearance in November.

Won't being on camera make a lot of extra homework for Culshaw and his impressionist colleagues, studying facial tics and body language? Apparently not. "You do those anyway. You can't help it. For radio you may be reading off a script, but when you're doing Tony Blair [slips into Blair voice] there will be the emphatic hand gesture, there will be the head tipped to one side. To get the voice you can't not do the rest. It's just instinctive."

The help of wigs and makeup in the TV version will bring added fascination for Culshaw, despite the amount of time they take. He recently recorded a show for ITV called Alter Ego (to be screened next month), a chat show in which Culshaw – as host – impersonates guests as he interviews them. It took seven hours to apply the prosthetics and make-up necessary to turn Culshaw (smallish, pink-faced, blond) into Frank Bruno, who, on meeting his doppelgänger, was "utterly mesmerised. He couldn't believe what he saw".

But Culshaw does relish the muscular challenge of using his own face – a face that bears a strong resemblance, as many have remarked, to that of Rory Bremner, an impressionist with whom Culshaw "has always got on extremely well". Like Bremner, Culshaw enjoys playing with his technical facility, and can't resist sharing professional discoveries.

"People say that today's politicians are too bland to impersonate. They even predicted satire would die. But if you watch someone enough, and television shows them often enough, something emerges from the fog. With John Major you home in on the top lip [his voice slips into Major mode] and then you discover he's quite like Julian Clary. If you do John Major and then make him a little bit flappier [same voice morphs alarmingly into Clary], you find they're very close to each other."

He says you can grow to like individuals in the course of studying them, but demurs on the question of whether doing a politician can influence one's politics. Unlike Bremner, he is not a political animal. "As I see it, there's three different teams and each wants the job." But this doesn't mean that when Dead Ringers goes to TV it will eschew political satire. Far from it. The only way management could justify commissioning Dead Ringers for BBC2 to run alongside Alistair McGowan's Big Impression on BBC1 was by securing assurances that Dead Ringers would be topical. Much of it will be written and recorded the night before transmission – a situation rare in mainstream TV comedy.

Existing Dead Ringers fans will be relieved to learn that the radio format will continue. "So many of its gags and characters are bound up with Radio 4 and don't transfer to TV," says Culshaw, following with a fond digression in the dark chocolate voice of radio newsreader Brian Perkins, to whom Dead Ringers has attributed a gun-toting, mafioso history, along with a steamy romance with the announcer Charlotte Green. The telly Dead Ringers will have to find its own targets.

Jon Culshaw will always do radio, he says, because that's where funny voices work best. He has never forgotten the exasperated calls from the programme controller when he was 19 and doing "the graveyard shift" (2am to 6pm) at his local station in Lancashire. The controller would say: "Just read the weather, in your own voice, not in Bob Geldof's voice, not in Frank Bruno's voice. Just read the weather and put the music on – and keep quiet."

Biography

1968 Born in Ormskirk, Lancs

1986 Stint as local hospital DJ

1987 Joined local radio as presenter

1990s Freelance impressionist on Radio 1 and Spitting Image

1998 Tricked Downing St switchboard into believing he was William Hague

2000 First series of Dead Ringers on Radio 4

November 2002 First series of Dead Ringers on BBC2