Audio: Jon Culshaw on Spamalot role

5 Live interviews impressionist Jon Culshaw, who will star as King Arthur in Monty Python's Spamalot in the West End.

With Rory Bremner no longer a regular presence on our screens, and the likes of Jon Culshaw, Alistair McGowan and Ronni Ancona failing to deliver much bite, there was a definite gap in the market for a risk-taking, quick-witted impressions show - until about three weeks ago, when this excellent series abruptly filled it. It showcases a handful of enjoyably sharp sketches lampooning the likes of Bear Grylls, Simon Cowell, the Gallagher brothers, Fearne Cotton and Amy Childs. Particular highlights are Brian Cox admitting that he buys his vintage leather jackets from Urban Outfitters, and Adele singing her drinks order to a barman in a pub.

Audio: Jon Culshaw's favourite impressions

Jon Culshaw gave BBC Radio 5 Live's Richard Bacon a snapshot of some of his favourite impressions.

Highlights included George W. Bush, Fabio Capello and Alan Carr.

Mr Culshaw will be presenting The Sky at Night's 55th anniversary as well as hosting Hyde Park's Jubilee Family Festival in June.

The final of Nigel Smith's The History Plays, a History of Blair in 9 1/2 Voices, was about the gap between image and truth. The brilliant premise here was that this was a conversation between two impressionists, Sue (Fiona Allen), waiting to do a BBC audition, and Blair (Jon Culshaw) whom she assumed was an impressionist who didn't want to climb out of character before being seen. "You've mastered the walk, like a peacock, both arrogant and anxious," she compliments him.

Culshaw doesn't just do Blair, he does him through the generations, redefining personality and accent. There are many lines which read like the pithiest of references: "No one had any idea you had principles until you invaded Iraq - on a point of principle." Though the play ends with the pair in a desert, stalked by grief, Blair remained a spooky presence, all spin with nothing substantive, an impression of an impression, which may have been the honest truth.

In terms of laughs-per-minute, this brilliant documentary profiling the life and work of the late Northern comedian Les Dawson is the one to beat tonight. Featuring many guffaw-inducing clips of Dawson in performance (sample quote: "I'd like to play you something by Mozart, but I won't because he never plays any of mine") as well as interviews with John Cleese, Jon Culshaw and others, it's a welcome celebration of one of the last century's most gifted comics.

I'm afraid Debra Stephenson's impersonation of The X Factor's Tulisa shows few signs of improvement (which is why Jon Culshaw's Louis Walsh has to keep addressing her by name).

To be fair, though, Debra's Claudia Winkleman (in her role as host of Film 2011) is still hilarious. Tonight we get Claudia's attempt at reviewing the new Tintin movie.

It's rare to find impressionists whose material matches their talent but for most of this enjoyable half-hour programme Jon Culshaw and Debra Stephenson have pulled it off. Both find moments to shine. Culshaw nails fashion consultant Gok Wan's slangy lingo and makes a suitably narcissistic Elton John. Stephenson shows us what it would be like to be stuck in a forest with Kirstie Allsopp and excels with her uncanny take on a breathless squinty-eyed Claudia Winkleman.

What happened to impressionists? There was a time when it was the blue-chip form of light entertainment, and no weekend or Christmas was complete without a special. But the steam seems to have gone out of it a little these days. The Impressions Show has its moments (Debra Stephenson gets that mad vamp off Dragons' Den to a T and Jon Culshaw nails Paul McCartney and Prince Charles). But all too often if you close your eyes you wouldn't have a clue who was being lampooned. It gives an impression of being entertaining, but not always a convincing one.

Jon Culshaw and Debra Stephenson offer up another 30 minutes of pretending to be other people. When the show hits home, as in a MasterChef skit where John Torode and Gregg Wallace reckon the contestants are "like cows at an abattoir", there's much fun to be had. Paul McCartney reforming the Fab Four with "all of the surviving Beatles except Ringo" and the Gok Wan wok gun also hit the mark. At other times, though, don't be surprised if your attention drifts: the show is consistently inventive without necessarily being consistently funny.

The Impressions Show saw Debra Stephenson miss two open goals with Hilary Devey and Tulisa. But with her physique, her Mary Portas, Claudia Winkleman and Fiona Bruce were exactly like the real thing - only foxier.

Jon Culshaw on the other hand was such a car crash his impersonations were more fascinating. His 'Bruce Forsyth' was bang on - if it had been Alex Ferguson, while his 'John Bishop', was the spit of Laurence Llewelyn Bowen. Final score? Debra Stephenson 5 - Jon Culshaw 0.