Last Night's Viewing: Life's Too Short, BBC2 - Rev, BBC2

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.

Rev is a much kinder comedy, and prompts a different kind of question, which is, how kind can a comedy get before it stops being funny? The success of the first series means that they can show off with a big-star cameo too; in this case, Ralph Fiennes, who did an eerily pious turn as the Bishop of London. Due to a misunderstanding, Adam finds himself up for a Pride of Britain Award he doesn't really deserve. With little more than a penetrating gaze of Christian understanding, the Bishop gets him to own up and forgo his moment in the limelight. It was a scene suffused with moral seriousness, but it didn't deliver a lot of laughs. The show is better (and more lovable) when it seems to celebrate human weakness. But then it's lovable enough itself to be forgiven the odd shortcoming.