Stephen Fry and his contestants don colourful scarves for a festive edition of the highbrow quiz show that loves a bit of low humour. Brian Blessed gets into the spirit on the subject of ice with some windy anecdotes about the Yeti and his love of husky dogs.

Sean Lock and Ross Noble are the quick wits riffing on Icelandic banking and prawns, while host Fry adopts his stern headmaster persona whenever his "class" seem to be having too much fun.

Like many teachers in the old-fashioned mould, though, he finds his own enjoyment peeking at the sight of one of his boys being humiliated... tonight, it's Lock falling off a chair.

If you've ever failed to work out the precise purpose of QI, it may help to think of it as in some respects a kind of televisual equivalent of I'm Sorry I Haven't A Clue. The show's very pointlessness, unless you're someone with ambitions to bore for Britain on arcane knowledge, is a great part of its charm. Anyway, this year's Christmas episode finds Stephen Fry posing questions on the theme of ice to Brian Blessed, Sean Lock, Ross Noble and Alan Davies.

The Now Show Preview - A Blessed Tribute

Guests on tonight's Now Show include Marcus Brigstocke, Andi Osho, Laura Shavin and Mitch Benn. In fact, here's a preview of Mitch right now with his affectionate tribute to Brian Blessed, who's been in the news this week.

After a week of such iconic women in their pomp, it is odd to come back into a world that has Big Top - the new sitcom starring the Britain's Got Talent judge Amanda Holden - as part of its cultural furniture. And at 7.30pm on BBC One, this is a big, spendy piece of furniture: like a wardrobe from Heal's, or a new double bed.

Last seen in a dramatic role as she unexpectedly burnt to death in Wild at Heart on ITV1 while trying to save a trapped giraffe, Holden's return is in a no-less baffling set-up: as "Lizzie the Circus Maestro", she runs a circus of what appear to be educationally subnormal friends and relations, in the "north Staffordshire area".

Despite a cast list of putative all-killer no-filler - Tony "Blackadder" Robinson, John "Fast Show" Thomson, Ruth "Hi-di-Hi!" Madoc and, in the first episode, even the handsome Patrick Baladi from The Office - Big Top comes from a school of sitcom acting where technique boils down to saying the words LOUDLY and rolling your eyes - much like Brian Blessed asking for a glass of white wine in the pub, on behalf of a male companion. The fact that there's a "comedy foreigner" who gets his words mixed up, and Thomson has to deliver lines such as "We need to catch those escaped ferrets - without the audience noticing!" only adds to the viewer's liverish sense of doom.

Of course, in the scheme of things, quibbling about the supporting cast here is like kicking up rough about the bread in your s*** sandwich: this is a sitcom starring Amanda Holden. I don't want to be proscriptive about comedy (it's a wide church, it's a deep well, it's often a mystery) but, by and large, it tends to be the preserve of people who can move their faces around a bit. Who knows the reasons behind it, but here Holden has as much facial motility as a seized gearbox. When she bangs home a punchline, it's like watching someone play Tetris at half-speed. I've seen tectonic plates break into a smile faster. She does, however - despite working in a big tent full of sawdust - wear incredibly tiny miniskirts and strappy heels throughout.

At the end of half an hour, a quick burst of data input into the standard-issue Viewer's Calculator reveals that, were the awfulness of Big Top rendered into miles, we could use it as a bridge to the Moon.

Review of the Brian Blessed episode

Whatever genius came up with the idea of letting Brian Blessed host an episode needs a hefty pat on the back and a firm handshake to boot. The man was pretty much single-handedly responsible for the funniest episode of the show in some time.

The Museum of Curiosity, Radio 4

Doesn't a little bit of Brian Blessed go an awfully long way? I thought of this whenever he opened his mouth on Radio 4's new, well, I suppose strictly speaking it's comedy, because it goes out at 6.30, but 'Radio 4's new comedy show' doesn't quite seem to fit. How does one describe The Museum of Curiosity? It's got guests; it has two hosts, Bill Bailey and John Lloyd, and occasionally, laughs.

Apart from Brian Blessed, of whom I have now had a sufficiency that will last me the rest of my days, the show more or less worked. Eccentricity is fine by me, as long as it's genuinely amusing. And hearing about Sean Lock's time as a goatherder - or Richard Fortey's experience of being stung by a giant Chinese hornet, or his story about the womanising museum curator who filed snippings of pubic hair from every woman he slept with - help pass the time pleasantly enough.

Last night's television brought us the sight of Brian Blessed bellowing a serenade at an understandably bewildered old woman in a hospital ward. "Oh, I fancy you like mad!" he then roared at her. This was followed by John Travolta chasing Cliff Richard, who was dressed as a giant leek - while Princess Anne looked on.

Any cabinet ministers watching may well have feared they were having a pot flashback. In fact, though, these clips (and plenty more like them) signalled the return of TV Heaven, Telly Hell on Channel 4.

Television about television is usually dismissed as self-regarding and unimaginative - which might even be true. On the other hand, it's also responsible for some of the most enjoyable programmes around, including Harry Hill's TV Burp and its upmarket BBC4 cousin, Charlie Brooker's Screenwipe.