For this second series, impressionist John Culshaw and ex-Corrie actress Debra Stephenson have a raft of new caricatures to add to their repertoire. Highlights include a typical night in chez Tim Burton and Helena Bonham Carter.

Jon Culshaw and Debra Stephenson interview

Now that they're back for another series of their Impressions Show, we gave Debra Stephenson and Jon Culshaw a ring to chat about the impersonating business, Eamonn Holmes's less-than-thrilled reaction to their send-up of him, and why Lady GaGa takes fashion advice from them...

Debra Stephenson interview

Debra Stephenson is going back to her roots with a second series of The Impression Show, alongside Jon Culshaw...

You'll recognise the name of Bill Dare as creator/producer of such programmes as Dead Ringers, The Now Show and I've Never Seen Star Wars. Here's a new series of a more recent invention, intertwining fantasy with the familiar. Lionel Blair, for instance, is mistaken for Tony Blair and has to go to the Middle East to get the leaders "dancing to the same tune", Al Pacino stalks John Humphrys. William Hague talks to the Ambassador of Kyrkistan having been mistakenly briefed on Uzbekistan. Jon Culshaw and Lewis MacLeod are among the skilled vocal parodists.

I'm Rimsky-Korsakov. I've got a brother at home - he's got a cold on his chest. We call him Nasty-Chestikov. Boom-boom. My girlfriend used to be in a circus. She chewed hammers. Was she professional? No, hammer-chewer.

Shall I stop now? In the early 1950s a comedy new wave was breaking on the shores of the Light Programme. Spike Milligan and Michael Bentine were breaking all the rules in Crazy People, later The Goon Show, while the improvised In All Directions featured Peters Ustinov and Jones in a Beckettesque road movie, driving round in a perpetual search for Copthorne Avenue.

But some of the emerging talent cleaved to more traditional comic values, as evidenced in my intro. Eric Morecambe and Ernie Wise's idols were Abbott and Costello and the Marx Brothers, and it showed in their rat-a-tat routines. Apart from playing the perfect straight man, Wise took it upon himself to be the duo's archivist, and he recorded a stack of material which lay in suitcases in his garage for decades. "I don't think he ever played them back," his widow, Doreen, told Jon Culshaw in Morecambe and Wise: The Garage Tapes. "He just knew he should keep them." A wise decision, given the BBC's historic penchant for wiping stuff.

The elements we know and love from the TV shows are all there: the bad playlets, the song and dance routines, the guest stars ripe for mickey-taking, though not the stellar names of later shows. Then, it was the likes of Jack Jackson, Brylcreemed trumpeter and Housewives' Choice disc-spinner, or Brian Rees, star of The Adventures of PC 49 ("surely you remember his catchphrase 'Oh, my Sunday helmet!' "). It feels like aeons ago, not just half a century.

When the pair first tried to break into TV, in 1954, it was a disaster. For the rest of his career Eric carried round the Express review: "Is that a television I see in the corner of my living room? No, it's the box the BBC buried Morecambe and Wise in last night."

Review: Morecambe and Wise The Garage Tapes

Much of the material that Jon Culshaw played in Morecambe and Wise: the Garage Tapes provided ample evidence for an opinion I have held for years - namely, that Eric Morecambe and Ernie Wise were of their time because they just weren't very funny.

Radio 4 listeners have been hearing trailers for this show for days so they may well think, when they settle to the whole thing, that they've already heard the best bits. Jon Culshaw opens the very case that contained old tapes and acetate recordings of Morecambe and Wise's early broadcasts form the 1950s. Ernie's widow, Doreen, found them in their garage and took them to independent producer David Prest who, with Stewart Henderson, crafted them into this essay on the development of the duo's comic style from variety act to TV stardom.

The "roast" is an odd American phenomenon, a sort of testimonial showbiz party during which the guest of honour is mercilessly insulted by fellow celebrities. The tradition began at the Friars Club in New York and was televised as part of The Dean Martin Show in the 1970s, and more recently on Comedy Central. Now Channel 4 is bringing us a British version, Comedy Roast, with Bruce Forsyth as last night's inaugural dishonoree. Jimmy Carr, Jonathan Ross, Jon Culshaw and Jack Dee were among his genial tormentors - a "Who's Who of who was available," as Carr said. It looks as if they went through the Js of some publicist's email address book.

There's a problem with insulting Brucie: it's hard to get beyond his age. "When the dinosaurs died out he was taken in for questioning," said someone. "He's seen Halley's comet three times," said someone else. A lot of the jokes overlapped. Variations on "Nice to see you, to see you nice" abounded. Jonathan Ross said "fuck" a couple of times, but the whole thing lacked the sleazy exuberance of the original format (you can watch the Dean Martin ones on YouTube). Only Bruce himself seemed to catch the spirit of the thing. "That was funny," he shouted at Jack Dee. "I knew you'd make me laugh eventually."

Although it might not sound it, a roast is the ultimate honour for any entertainer. First started at the New York Friars' Club in the 1920s and made famous by Dean Martin on his TV show in the 1960s and 1970s, a roast involves you sitting in a room with your friends, family and colleagues as they mercilessly take the mickey out of you - goodnatured bullying, as the host Jimmy Carr calls it. There are three roasts this week - don't miss Sharon Osbourne's on Thursday and Chris Tarrant on Friday - but first up is Mr Showbusiness himself, Bruce Forsyth. Lining up to pay mocking tribute are Jack Dee, Jason Manford, Bruno Tonioli, Arlene Phillips, Jon Culshaw, Barry Cryer and, best of all, Jonathan Ross. It may be sycophantic, but there are still some hilarious moments.

Looking back, Debra Stephenson was wasted on the likes of Bad Girls and Corrie, much though I loved her in both roles. Having teamed up here with the splendid Jon Culshaw, she's able to remind us what a fabulous and versatile mimic she is.