Tom Sutcliffe

Snodgrass, David Quantick's drama for Playhouse Presents, imagined a world in which John Lennon had walked out of The Beatles before they made it big. The only zebra crossing he strides over in this universe is the one on the way to the job centre, his only fame that of a might-have-been. Ian Hart was excellent as Lennon and the script beautifully captured Lennon's aggressive wit. But the heart of the thing was that it wasn't really about Lennon at all. It was about that bit of us that aches to be a Lennon when we're 20 and still does 30 years on.

Last night's viewing - The Wright Way, BBC1

Like Dr Frankenstein, Ben Elton appears to have created his new sitcom, The Wright Way - his first for more than 10 years - by exhuming the body parts of different comedies and stitching them together. The result is an odd, lurching affair, sometimes funny but occasionally so groan-inducing that you want to gather a mob with torches and pitchforks.

I've caught up late with Plebs, Sam Leifer and Tom Basden's comedy about three also-rans in Ancient Rome, which turns out to be a likeable enough affair, though you never entirely feel that they get out of second gear when it comes to the writing.

I did laugh aloud when the lads' landlord indignantly accused them of "Thracism" for wanting to get rid of a Thracian tenant he'd foisted on them, but I think that was partly because the line was delivered by the wonderful Karl Theobald. Also effortlessly funny, even when saying nothing at all, is Ryan Sampson as Grumio the slave. Shades of Baldrick - the dimwit's dimwit.

Comedies are both the easiest and the hardest kind of programmes to review. On the one hand, it's really simple to tell whether it's worked, since there's actually an audible signal to register the fact. As with pornography, success is registered by a bodily response rather than a cerebral one. But, as with pornography, it's intimately a matter of personal taste. You can no more rationalise a third party into laughing than you can argue them into becoming aroused. From the involuntary wheezing noises that persistently interrupted my viewing of It's Kevin, I can be absolutely sure that it's my type of funny. The problem is that anything I write about it is doomed to be an elaborate paraphrase of "I just liked it". All I can hope to do is explain why.

Kevin Eldon himself is the obvious place to start, an enlivening spice in other people's sketch shows and comedies for years now, but here the headline act for the first time. And he can make you giggle just by looking at you, gifted with a face that can twist from bland normality to something gargoylish in an instant. For evidence, see the opening sketch, in which an aggressive drunk staggers down a hospital corridor, abusing the policeman and the nurse who are trying to guide him into a side room. When the camera closes in to look through the door, you see a surgical team ready to go and the same nurse vainly struggling to get the drunk into a surgeon's gown. It's a decent rug-pull, but Eldon's wild clowning gilds it.

Then there's the ingenuity of the structure, a ragbag of sketches and spoofs that pretends to be a free-form mess and is anything but. "Look, cards on the table... it's certainly not subtle or erudite..." said Eldon casually, introducing the format at the beginning. At which point, a giant boxing glove appeared from the side of the screen, whacked him into cartoonish grogginess for a couple of seconds before he snapped back to earnest sincerity "...but at least it's made by somebody who cares." That's a dumb joke and a clever one simultaneously, a trick he pulled off more than once.

Best of all, it keeps you on your toes, jinking from relatively straightforward sketches (including a lovely sequence in which Eldon plays Adolf Hitler as the Beatles' producer George Martin, languidly recalling the day "me and the boys marched into Poland... and I immediately knew we were on to something big") to more surreal self-reference. And it has the funniest and most engaging title sequence I've seen for a long time. And it even had a joke about pornography, when Eldon's secret stash is retrieved from the couch he's sitting on and turns out to consist of a publication called Mildly Flirtatious Ladies. What can I say? It really turned me on.

New Channel 4 comedy The Mimic appears to have been built around the ability of its lead actor, Terry Mynott, to do impressions and there are moments when you wonder whether he provides a solid enough foundation. His Terry Wogan was very wobbly and his David Attenborough was a weird hybrid of Alan Bennett and Ian McKellen. Other impressions are so left-field they have to be visually signposted or cued up by a line of dialogue to make sure we get them.

But there was a promising little sequence as Martin (Mynott's character) sat slumped in front of his television and Morgan Freeman and James Earl Jones fought it out over who was best at adding gravitas to a natural-history programme. It's a comedy of underachievement essentially, complete with marimba noodling on the soundtrack to signal the underlying pathos, but it has some lovely downbeat moments and funny silences where some comedies might strive (unsuccessfully) for a big guffaw. Look out for Jo Hartley as Martin's friend Jean too. She's very good, so quietly you might miss it.

I have a feeling that viewers are now attracted to new comedies in a process similar to ant-colony optimisation. A few try it out and if they like it and return they leave a pheromone trail that attracts others, until eventually there's a swarm clustered round every juicy new episode. Not sure that it's going to happen with Heading Out, Sue Perkins' comedy about a vet plucking up the nerve to tell her parents she's gay, perhaps because it continues to strain credulity with its comic plots.

This week, one running joke concerned her friend Jamie's attempts to become more blokey, an ambition that never remotely threatened to become believable. On the other hand, the surreal moments at which the whole thing turned into a soulful French film, complete with subtitles, were quite funny. The latter seemed true to a state of mind, the former just faked one for the sake of a joke.

Anna & Katy, a new sketch show from Anna Crilly and Katy Wix, included a skit about a dinner party at which no one could recognise a joke until it was laboriously pointed out to them, at which point they roared completely out of proportion to the feeble quip that had been made. It was quite an interesting sketch but not terribly funny, which was also true of most of the programme, though some sketches made a little interesting go a very long way, including an interminable Countdown pastiche and a baffling spoof of daytime telly. These people can deliver a funny line, but they were struggling with a serious shortage of that particular commodity.

Old Roman joke: "That slave you've sold me has just died." "My God, he never did that when he belonged to me!" Ah well...perhaps you had to be there...and by "there", I mean a tavern somewhere in the Suburra around 40BC, because the gag didn't exactly bring the house down in Michael Grade and the World's Oldest Joke.

In fact, it died, along with a startling number of other historical jokes and quite a few contemporary ones, the producer of this otherwise intriguing exploration of the history of the rib-tickler having taken the perverse decision to give the job of telling the gags almost exclusively to people who weren't very good at it. What Michael Grade was interested in was the embedded human need to crack wise. What the director seemed to be interested in was getting in the way as often as possible, quite often with members of the public mangling perfectly blameless jokes.

To be fair, it was hard to imagine anyone being able to revive some of these vintage gags. Take this, from a Tudor compilation of humorous quips - Q: What is the cleanliest leaf? A: The holly leaf, because no one will wipe their arse with it. Or the jokes that depended on the reliable hilarity involved in beating your wife. And once the programme had calmed down a bit - and got away from the philosophising about the nature of comedy that also bogged down the opening - it proved interesting. It was good to learn about Poggio Bracciolini, a papal employee who compiled the Liber Facetiarum, an early joke book full of stuff that only a cardinal could read without blushing. And I liked the revelation that the Greek passion for lettuce gags was dependent on the belief that it was an aphrodisiac. Substitute Viagra for the little gem and most of them would (half) work now. The oldest joke in the world, incidentally, was a fart gag, which seemed somehow comforting. A warm, gently rising fug of carnality.

Last night's viewing - Bluestone 42, BBC3

I think Bluestone 42, BBC3's new comedy about a bomb-disposal team in Afghanistan, may be unique. Of course, there have been other sitcoms that tried to see the funny side of a bloody war before now. M*A*S*H did it brilliantly, as did Blackadder Goes Forth. But neither of those series went out while the war in question was still underway.

Last night's viewing - Heading Out, BBC2

First impressions weren't bad, though there may be people who don't feel quite the same way about the boldness of introducing your new series with a joke about feline euthanasia.