The Mimic/Anna & Katy, Channel 4

It’s a truism of the impersonator’s art that those who can do other voices have none of their own. On Parkinson, Peter Sellers couldn’t even come down the staircase as himself. When at the end of the show Mike Yarwood said, “And this is me!” a nation switched off. The idea behind The Mimic, starring the remarkable Terry Mynott, is that it accepts the truism as truth. This is a comedy about a man who can pose convincingly as Ronnie Corbett stuck in a postbox but has no life to call his own.

Martin Hurdle – even his name sounds like a personality flaw - works in maintenance at a pharmaceutical company. There is no hope of promotion from whitewashing graffiti off walls, so he disappears into a multi-coloured vocal hinterland where he can be any number of camp television presenters or, in the sharpest sequence, James Earl Jones and Morgan Freeman engaging in a Socratic squabble over who has the better Afro-American larynx for narrating documentaries about penguins.

Female double acts are rare enough to be treasured

This ability has not brought Martin any more joy away from work. He lives with Jean (Jo Hartley), a female flatmate who is equally propping up the bar at midlife’s last-chance saloon. For all the richness of Martin’s interior life set against his humdrum routine, The Mimic could easily struggle to escape its binary parameters, but this first episode swiftly introduced a second outlandish scenario: Martin has discovered that he may have fathered a child 18 years earlier. It’s all subject to a DNA test, but when they meet in a pub, the boy is soon crossing his fingers that they won’t be related after all. This is a worry Martin articulates to himself through the conduit of Wedding Crashers. "If I didn’t know who this guy was, and it turned out to be this guy," says Vince Vaughn, " I would be pretty disappointed." Or was it Owen Wilson?

It’ll be worth finding out where The Mimic, already promisingly weird, goes from here. A lot rests on how series creator Matt Morgan marries two distinctly left-field scenarios – incurable impersonator discovers he’s sired an adult. It certainly revinvents a branch of entertainment that has felt for a while like a busted flush.

The same can’t quite be said for Anna & Katy. Female double acts are rare enough to be treasured, which is why it was no fun at all to see Watson & Oliver take an undeserved pasting in theartsdesk’s comment stream, mostly from blokes, when it debuted on the BBC last year. Anna Crilly and Katy Wix, who write as well as star, take light entz idioms as their springboard: Eurolottery shows, cookery programmes, workplace docusoaps, reality. The performances are a treat – Crilly’s turn as a dour housekeeper in Lead Balloon is clearly just one string to her bow – but the material doesn’t feel quite honed enough. There’s a dash of verbal incontinence, a bit of Gervaisery, some Dom Jolyesque physical surrealism and lashings of protean vocals. The most original gag features a Joan Collins-alike (pictured above right) who requires a prompter to tell her own life story. The funniest line in this episode came as Martin Kemp (one of several game guest stars) plugged his new CD on a Benelux channel. “Great piss!” said Dix's enthusiastic presenter.  After two episodes this is more like quite good piss.