You could get some idea of how nervous the BBC was about Life's Too Short (Thursday, BBC Two) by the documentary it put out beforehand which made it perfectly clear that its star, Warwick Davis, had not been cruelly press-ganged into appearing in a comedy about a dwarf. No, he'd actually done it of his own free will.

While Davis himself was very good, somewhere along the line co-writers Stephen Merchant and Ricky Gervais seem to have forgotten to give him much of a character. Instead, he was another bumptious, insecure actor, forever puffing himself up - albeit one who's only 3ft 6in tall. Easily the best scene came, not with Davis, but with the appearance of Liam Neeson playing a wonderfully humourless version of himself.

What made this so good was that it tapped into the dolefulness to which Neeson, one suspects, is prone. Yet while he and Davis suffered from the lack of self-awareness that's the hallmark of Merchant and Gervais's comedy, Davis's brimming optimism in the face of divorce and bankruptcy just seemed a bit sad by comparison.

So, are we laughing at the dwarf or are we laughing with him? Once you'd decided which side of the height-challenged fence you were sitting on, you could get on with the rather more important business of deciding whether new Ricky Gervais comedy Life's Too Short is any good or not.

And it is - good, that is - in a 'law of diminishing returns, it's not The Office', kind of way. Gervais and Stephen Merchant are masters of the faux-documentary genre and, in Warwick Davis, Life's Too Short's dwarf-in-residence, they've found the perfect vehicle for taking the rise out of egotistical self-delusion. Which, come to think of it, is pretty much what all their stuff is about.
Built around a video diary documenting Davis's disintegrating life and career - from the heights of a Star Wars Ewok, he's now reduced to begging for crumbs from agents Gervais and Merchant - Life's Too Short has as little to do with life as a dwarf as Towie does with Essex. It's about scrambling for survival on life's seething ant-heap: and if that means a spot of Ricky - grovelling, so be it.

'How does he get away with it?' pondered Liam Neeson of Gervais's career. He'd stopped by at Gervais's office for comedy tips and proceeded (hilariously) to reveal a total sense of humour bypass. How indeed? Gervais's smug style hovers on the jokey butt-cheek of self-parody but, even though you know he's laughing at us, not with us, you can't stop yourself from giggling.

One of the questions you might ask about Life's Too Short, the new comedy from Ricky Gervais and Stephen Merchant, is how it would have worked if its central character wasn't a dwarf. Life's Too Short is built around an actor called Warwick Davis, who plays a comically tweaked version of himself. Like the real Warwick, this one was an Ewok in Return of the Jedi and runs a talent agency hiring out other dwarfs ("I've had a lot of success and this is my chance to pay that forward"). Unlike the real Warwick (I assume), this one is in the middle of a messy divorce and looking for a way to pay off a massive tax bill. And one of the striking things is how much of the comedy depends less on his physical stature than on his status, as a man whose opinion of himself is considerably larger than the world's. Warwick is playing Warwick but he's also playing Brent/Millman/Gervais, that slippery amalgam of real character and comic invention that props up nearly everything Gervais does.

You saw it again and again, in the unmistakably Brentish way that Warwick added self-serving footnotes to embarrassing footage ("Oohh..." he said nervously, as his estranged wife lets rip. "Showing off"); in the little sideways glances at the camera; in the unwitting revelations of his self-centredness. None of those jokes would be substantially different if Davis was two feet taller. Similarly, Warwick's incompetent accountant (who doesn't know how to do percentages on his calculator) would be equally funny with an averagely sized client. And the cameo in which Liam Neeson turned up at Gervais and Merchant's office for advice on comedy improvisation didn't even need Warwick to be in the room (though he actually was there, keeping a chair warm). A lot of it, in other words, would have worked in exactly the same way, though it would have been a good deal more vulnerable to charges of recycling.

Which leaves us with the jokes that are inextricably related to Davis's height. Some of these play mischievously with prejudices. "You're a dwarf. How can you not know 'Heigh-Ho, Heigh-Ho'?" Warwick said to one of his performers incredulously. Others exploit his height, such as a long sequence in which he had to enlist a scornful passer-by to help him get into Gervais and Merchant's office (the door buzzer was too high). And one or two edge us uncomfortably close to simply laughing at little people. As Warwick pompously compared himself to Martin Luther King and talked of his dream that "one day dwarfs will walk equally", his rhetoric was undermined by the sight of him falling out of his car. It's a punchline moment, but is it a joke about a self-deceiving man or one whose legs don't reach the ground? I'm still not entirely sure, and I suspect that Gervais in particular would be happy about that. If you want to take offence, be his guest. He's certainly made it easy for you. But be warned that you may have to suppress a laugh as you do it, and then think about what exactly you're suppressing.

If you saw Karl Pilkington's recent Sky series An Idiot Abroad, you'll have seen him phoning Britain's leading dwarf actor Warwick Davis to check whether a Dwarf Village he'd visited in China was politically correct. Davis assured him, quite angrily, that it wasn't.

So you might be surprised to find Davis starring here in another dwarf-based jape, also made by and featuring Stephen Merchant and Ricky Gervais.

In this mockumentary, Davis plays a version of himself as he attempts to raise his profile as "a sophisticated dwarf about town". It's screamingly funny, and if Davis chooses to send himself up, who are we to judge?

Nobody complained when he played an Ewok, which is ­basically a sci-fi teddy bear.

Shaun Williamson is in it too - continuing his gag from Extras, but the funniest bit is a cameo from Liam Neeson who reveals he's branching out into comedy.

Miss this at your peril.

This spoof documentary from Ricky Gervais and Stephen Merchant, starring 3ft 6in actor Warwick Davis as a fictionalised, David Brentified version of himself, contains all their tricks: bemused expressions; awkward looks to camera. But it takes no prisoners and is very funny. Davis displays fine comic chops as he hustles for acting work, mismanages his finances and grapples with his failing marriage, plus there's a cracking scene with Liam Neeson failing to grasp the basic concepts of comedy.

I sat before Life's Too Short, arms crossed and daring it to be funny because I really wanted to be offended AND unamused. A comedy series about dwarves? Who the hell would write such a thing? (Ricky Gervais and Stephen Merchant.)

But Life's Too Short isn't a comedy about dwarves, though it does have a dwarf star - the urbane, winning Warwick Davis, a dwarf actor (Return of the Jedi, Harry Potter) down on his luck. His wife's thrown him out, he's almost bankrupt and the work has dried up. Even clients at his dwarves-only casting agency are bad-tempered and resentful.

Though it stars Gervais doing his Gervaisy thing (the sly looks to camera, the faux puzzlement) he is eclipsed by Davis playing a version of himself. But everyone is overshadowed by Liam Neeson, who is majestically unfunny as a humourless Liam Neeson ("I'm always making lists. That's probably why Steven Spielberg
cast me as Oskar Schindler") who earnestly wishes to become a stand-up comedian.

Anticipating the flak Life's Too Short might provoke and opting to get his revenge in first, Ricky Gervais last week announced that he embraced the haters. After last night's first episode, it's not the haters Gervais need worry about. It's the thoroughly indifferent. The problem with this new series is not that it's offensive; it's that it's just not very funny. It took over eight minutes to raise the first smile - Warwick Davis falling out of the 4x4 - and the only real laugh came near the end when Liam Neeson tried to pitch a stand-up routine about Aids.

It all just seemed too familiar; partly because any element of surprise had long since gone thanks to the endless preview trailers and the PR campaign to reassure everyone that the show was basically politically correct, but mainly because it felt like the show you'd have written yourself if you were trying to write like Gervais. Push the boundaries of taste. Tick. Blur the real and the imagined. Tick. Rope in a few celebs. Tick. Take the money and run. Tick.

For those fortunate enough to miss all the hype - there must be one or two of you, I guess - Life's Too Short is a mockumentary about a dwarf actor whose career and marriage has hit the skids and is hoping to revive both by making a reality show of his life. In theory, this is as good a starting point for a comedy as any other. Failure, anger, hubris and self-delusion are key building blocks of much humour and there's plenty of potential for all four. Only it's seldom realised.

It's not so much Warwick Davis as the dwarf who is the problem, but Gervais and, to a lesser extent, his sidekick, Stephen Merchant. There's only so long you can go on writing and performing the same type of characters without boring your audience and the pair have passed the point of no return. We've seen Gervais humiliating Merchant in Extras, we've seen them both humiliating Karl Pilkington in An Idiot Abroad. And the joke has worn thin by the time they play Warwick Davis's agents and bully him.

Increasingly, also, Gervais' own ego is getting in the way. There used to be a tension when real celebs started showing up in Extras because there was a lingering sense that they didn't quite know what they had let themselves in for and that the joke might be some way on them. That ambivalence is now long gone.

Gervais' own desperation for fame is now utterly transparent. Having seen him crave Johnny Depp's approval on The Graham Norton Show last week, it's become impossible to believe in his indifference to celebrity. Which rather kills the gag. And while you can't not be happy for Gervais that he's achieved the recognition his genius deserved, it's a bit of a shame for the rest of us that it seems to have - temporarily, I hope - nobbled his talent.

It's become clear that Ricky Gervais and Stephen Merchant are never going to make anything like The Office ever again. And, as they've said themselves, why should they: having created sitcom genius and revolutionised the genre, they are hardly likely to top it.

It's become clear that Ricky Gervais and Stephen Merchant are never going to make anything like The Office ever again. And, as they've said themselves, why should they: having created sitcom genius and revolutionised the genre, they are hardly likely to top it. What they did for an encore was Extras, which mocked their entry into the showbiz elite, yet celebrated it by bringing in all their new pals to amusingly send up their public images. They foisted the tedious witterings of their non-famous pal Karl Pilkington upon us, until he was in showbiz too. And Ricky made some disappointing movies and popped up in all his American showbiz mates' TV shows and on his pal Jonathan Ross' chat show and annoyed everyone by being offensive on Twitter (but maybe it was just him pretending to be offensive, except that still involved offending people, but they weren't his friends so they didn't really count). And meanwhile Stephen, er, did some "ironic" bank adverts.

OK, they did make the film Cemetery Junction, which wasn't about fame at all, but not many people saw that. Instead, Gervais in particular has seemed to relish spending his time in the public eye portraying a smug, annoying celebrity character to the point where the last line of Animal Farm seems to apply - looking "from pig to man and from man to pig ... but already it was impossible to say which was which".

So it is, ahem, small wonder that the pair's latest venture returns to that well, starring their showbiz chum and Extras guest star Warwick Davis, in a faux-documentary sitcom about a dwarf actor who runs an agency for other short actors (as Davis actually does) but who can't get any work for himself, even when he begs Ricky Gervais and Stephen Merchant to write him something. Confused? Yes, that's the point: life's too short revels in the boundaries between the real and the not-real, with most of the characters using their actual names, while playing themselves as venial twits.

The similarities to Extras can barely be overstated. While Davis has the starring role - and it was apparently his idea - the dialogue makes him actually sound like Ricky Gervais: you can hear those Brentian speech rhythms leaking out. It's oddly reminiscent of the recent films of Woody Allen, where he drafts in various young actors to play the "Woody" character and they all end up imitating those familiar nervous tics. Here, it's difficult not to hear Gervais's voice behind Davis's lines, such as: "I'm a bit like Martin Luther King, because I too have a dream that one day dwarves will be treated equally ... you say, oh no, it's not the same ... but I've never seen a black man fired from a cannon. Every day for a whole season and twice on Saturdays."

It's not the fault of Warwick Davis, who's absolutely fine in the role of a hapless fictional version of himself and clearly well up for any resulting confusion it may cause. But there's just so much of Gervais and Merchant, both in the references and on screen, that he's in danger of being squeezed out of what's meant to be his own show.

The show shares Extras' fascination with celebrity cameos and when Liam Neeson pops up to consult Gervais and Merchant, playing "themselves", on his stand-up comedy plans, Davis is relegated to the background while they milk the scene, surrounded by posters reminding us of all their previous work. Like Extras' Andy Millman, Davis' character has a useless hanger-on: instead of an agent, it's his accountant (Steve Brody, who was David Brent's useless agent in The Office Christmas Special). Even Barry Off Of EastEnders turns up, still playing the same loser.

Well, plenty of people loved Extras, of course, but given that it was a self-referential take on Gervais's own rise to fame, isn't making a meta-parody of it just a post-modern gag too far? But worse than that, the joke isn't all that funny anymore. There are a couple of laughs here, for sure (mostly from Neeson's bit), but the whole thing just seems like an indulgent, back-slapping waste of talent.

"My name is Warwick Davis. I'm the UK's go-to dwarf." Four years on from Extras - and eight since the last episodes of The Office - Ricky Gervais and Stephen Merchant return to their mockumentary roots with this excruciatingly funny sitcom starring 3ft 6in actor Warwick Davis as a rather down-at-heel version of his real self. Trailed by a camera crew making a documentary about his life as a film star and dwarf talent agent, Warwick - who's been in everything from Return of the Jedi to the Harry Potter movies - has hit hard times and is keen to brush over embarrassing realities and make a good impression. "I want people to see a sophisticated dwarf-about-town who carries himself with dignity. I'm a role model, a bit like Martin Luther King..."

Making viewers feel as uncomfortable about their political correctness as their prejudice is Gervais and Merchant's stock in trade, and the cringe-making moments pile up relentlessly. They also revive a key ingredient of Extras, cramming the series with as many celebrity guest appearances as possible. Liam Neeson gets the lion's share of the self-deprecation tonight, although Extras regular Shaun Williamson also gets to make a familiar contribution.

Reality and satire get even closer in this latest offering from Gervais and Merchant. In this supposed documentary series, we follow actor Warwick Davis, "the UK's go-to dwarf". Davis plays himself as a cross between David Brent and Tony Blair, a man with a delusional sense of his own importance, who sees himself as a valued character player, and campaigner ("like Martin Luther King") but who sees others of his stature as slightly pitiable. Liam Neeson guests, expressing a wish to debut his spectacularly unfunny standup comedy.