Last Night's Television - Deborah 13: Servant of God, BBC3; Horne & Corden, BBC3

One wonders how the first instalment of Horne & Corden would have managed without James Corden's belly, a comedy prop so central to the first episode of their new sketch series that it surely deserved a billing of its own. It was, after all, the indispensable star of the first filmed sketch in last night's show, in which Bloke One and Bloke Two wandered up to a burger van chatting idly about last night's match, until suddenly Bloke One noticed that Bloke Two was carrying enough around his middle to warrant an excess-baggage charge on a Ryanair flight. Bloke Two screamed appalled – as if the blubber had suddenly appeared without warning – and proceeded to berate Burger Van Man for the effects of his merchandise, while Bloke One got a strong grip on the overhang and proceeded to jiggle it wildly, to demonstrate the scale of the problem. The studio audience, as far as one can tell, went wild for this gag, though judging from their hysterical behaviour when Horne and Corden danced down the studio stairs, they were predisposed to like whatever came next.

The sketch show, one takes it, is a reward for Gavin & Stacey. Or what marketeers like to call a brand extension, venturing out from straightforward sitcom into Morecambe and Wise territory (or Alas Smith & Jones, or perhaps, if things go very badly, Little and Large). In the studio, Corden played the silly, over-excitable one, prone to bouncing around in a Tiggerish way, while Mathew Horne did the straight-man stuff, trying to stick to the script in the teeth of his co-star's excesses. In the sketches – both filmed and performed live in front of the audience – they shared things out a little more equitably. In a foreign-correspondent spoof, for example, it was Corden who played the sober anchor and Horne who took the part of a wildly camp and flamboyantly highlighted reporter. "What can you tell us about the present situation?" asked Corden gravely, brow furrowed to convey the gravity of the story they were covering. "Oh, it's mental!" fluted our man in Basra. "Honestly, it's all going off here... It's nuts!" Asked about the current climate, he replied, "It. Is. Baking!... Honestly! It's sweltering out here!"

They're both talented comic actors (Corden, in particular, did a note-perfect piss-take of Ricky Gervais, scene-stealing shamelessly as he performed in a remake of The Karate Kid), so where there were dips, it was usually the result of material rather than delivery. And, though it would be ridiculously early to write it off, it was worrying that their opener should have been so reliant on material that struck you as a bit end-of-term-revue in character. Corden's naked body was treated as a kind of get-out-jail-free card, with no less than three sketches in which he got his kit off and at least one more in which the only gag derived from his weight. They clearly know their audience, though, because in every case the studio laughter spiked as the clothes were peeled off. I hope subsequent episodes will conduct a bit of comic liposuction, and lose the belly in favour of the stuff they actually require a keyboard for.

Deborah 13: Servant of God, a film about a devout evangelical teenager, began with a scene in which the offscreen director exposed just how sheltered she and her siblings were from the modern world. Deborah had no idea who Victoria Beckham was and she politely asked for Britney's surname in the style of someone asking for an extra clue. Deborah won't be watching Horne & Corden, which is a mercy, really, since it's pretty filthy at times, and Deborah thinks that even white lies are deserving of an eternity in hellfire. Shortly after failing her A-list identity parade, she launched into the film's director, claiming that she was a "lying, thieving blasphemer" and thus on a fast-track to damnation.

There are a lot worse things than not knowing who Posh Spice is, of course, and there are a lot of people – not just the devout – who might think that not knowing who Posh is is actually a good thing. And as you looked at Deborah's life – home-schooled on a Dorset farm and preternaturally detached from anything that might count as typical teenage life – I found it hard to get very worked up about her faith, even as a hair-trigger atheist. Yes, she was a bit dreary when she pulled out her tracts and started to preach, but then a lot of teenagers go through sanctimonious phases. And yes, she was horribly ignorant about science and evolution, swallowing Creationist gibberish without a second thought. But when she went out for a night on the town in Derbyshire with her student brother, and a young fresher staggered up and asked, "Does someone want to write on my boobs?" you couldn't help – for one flickering moment – seeing the world through her eyes. Buxton, the Gomorrah of Derbyshire.