If our relationship was a marriage it would be sexless

David Mitchell and Robert Webb are past pretending they're the best buddies on British telly. After 16 years together, the dynamic of their relationship has changed. If it was a marriage, it would be a sexless one by now they say.

That Mitchell & Webb Look episode 4.1 review

This opener for the fourth series was underwhelming, and it irritated me that David Mitchell and Robert Webb have chosen to stick with the Get Me Hennimore and Remain Indoors sketches, which both ran out of steam halfway through series 3. Still, as usual, Mitchell & Webb's work never patronizes its audience and doesn't rely on recycling jokes and catchphrases, so for that I'm grateful and will still be tuning in.

"I'm a sex champion, and I'd like a trophy," declares Robert Webb, setting the gloriously quirky tone for a sketch show which, at the start of its fourth series, seems to have lost none of its originality. David Mitchell is perfect as the conscientious small shopkeeper who gamely cobbles something together using a snooker player and a badminton figurine. The skits range in subject from the timeless to the contemporary, puncturing pomposity whether the subject is Caesar referring to himself in the third person (and getting very confused in the process) or Apple's cooler-than-thou advertising campaigns. Even the fact that the duo once promoted the Mac themselves hasn't detered them.

As ever with this duo, most famous for their roles in the deliciously dark Channel 4 sitcom Peep Show, their verbal flair is evident. A generic 1970s-style company is called "Amalgamated Perforations", neatly skewering the meaninglessness of corporate language, while the head of a leading cosmetics laboratory berates his team of scientists for "wasting their time" on making genuine scientific breakthroughs. "Does perpetual motion do anything for the Sleek and Shiny range?" he demands huffily.

There's also a sketch about a couple who are forever having vicious arguments in front of their baby. The couple are played by Webb and his real-life wife, Abigail Burdess; although we presume the sketch has no autobiographical basis...

It's never easy sizing up a new series from David Mitchell and Robert Webb. In a previous series the pair performed a skit about the fact that critics invariably refer to sketch shows as "patchy"; tonight they play super-serious versions of themselves who dismiss the show as "a sneering pantomime of impudent crud". They've basically spiked your guns before you start. So I'll limit myself to this: the first episode is very funny at times, less funny at others, but all enjoyable. And if you've ever been annoyed by people pronouncing "H" as "haitch", you're in luck.

It's impossible not to be cheered up by the return of Mitchell and Webb. They're unfailingly funny, even if their material isn't.

So let's get the bad news out of the way. Two running sketches - Get Me Hennimore! and the British Emergency Broadcasting Service - return, although they've been pretty much sucked dry of comedy potential already. And the first sketch is probably the weakest - a good idea that peters out before it finds its punchline. I can only advise you to think of Robert Webb doing Flashdance in his black leotard to top up the giggle level during the weaker bits.

But there's a brilliant sketch set in the white-coated world of Laboratoire Garnier which also features David Mitchell as a Victorian northern mill owner.

And two more skits are tailor-made for Mitchell's pedantry. He's one of the few comedians who can make grammar hilarious. There's also a guest spot from Keeley Hawes - well, she is in everything else these days.

Video: Mitchell and Webb return with a new series

David Mitchell and Robert Webb, the award-winning comics behind Peep Show, speak to BBC Breakfast about the fourth series of That Mitchell and Webb Look.

That Mitchell & Webb Look review

This new series won't disappoint fans but it's hardly likely to attract a new audience who have become suspicious of the sketch show as a genre following its sophisticated deconstruction in Chris Morris' Jam and Channel 4's Green Wing.

That Mitchell & Webb Look Returns

The excellent Mitchell & Webb return tonight on BBC Two at 9pm. Gareth Edwards, the producer of the show, gives an insight into just how unique the filming is.

Hmmmm. Are they Britain's best comedy duo? Probably. But all that leads to is a further hmmm. They're certainly Britain's most likeable comedy duo which is why it feels a bit like kicking a puppy to slag them off. No mind. Their sketch show is uneven. The good bits - a self-referential Caesar, perpetual motion seekers in the Laboratoires Garnier and a broadside on people who pronounce 'h' as 'haitch' - are very good. There's a healthy lack of returning characters. But still, other bits are just a bit lame.

At this point, a lot of reviewers say they miss Peep Show writers Armstrong and Bain but tvBite disagrees. Peep Show is a smooth operation and nicely crafted, but the pair don't write great jokes. Look at The Old Guys or Four Lions, creditable in their way but not containing the hilarity that would make a sketch show like this work better. Anyway, why dwell on what could be and not enjoy Britain's most likeable sketch show?

One last thing: Robert Webb

With That Mitchell And Webb Look returning, Robert Webb meets Rich Pelley to talk Wombles, David Cameron and wiping his bum on swans.