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.

There's only one way to get through Big Top

There's only one way to get through Big Top - by playing Guess the Gag, says Sam Wollaston.

Do we really have to speak about Big Top? OK. Big Top is a sitcom about a failing circus, inexplicably starring the wooden, joke-killing Amanda Holden as the scatty, though apparently strong-willed, owner. There's a trapeze artist madly in love with her, Ruth Madoc as a dog-handler, and other rather good actors (Sophie Thompson, John Thomson) flailing with a lame script. Patrick Baladi as a health and safety advisor was ejected at the end of episode one after failing to persuade Holden of the merits of a life of mortgage trackers and convention. Lucky him. Poor us.

Big Top, a new sitcom set in a travelling circus, is one of those programmes that get you wondering about the commissioning process. You'll need something to entertain you while it's on and speculating about the way it came into being will do as well as anything, unless you've got a dog that's overdue for a combing or some socks to pair up. One assumes that the performers' names came first on the pitch document. One certainly hopes that they came first on the pitch document, since the idea that it was sold on the essential concept and a sample of the writing seems implausible, to say the least. We've thought of a vehicle for Amanda Holden, somebody said, and what's more it's a role that will make it feasible for her to wear hotpants and black stockings nearly all the time. And if you bite there's a good chance that we can bolt on John Thompson, Tony Robinson and Ruth Madoc. How's that for belt-and-braces coverage? Cold Feet, Blackadder and a dab of Hi-De-Hi! behind the ears.

"So what's the sit?" asks the commissioning editor. Down-at-heel circus, replies the pitcher, run by Lizzie, a mildly over-controlling ringmistress who's the only grown-up on payroll. There's a terrible husband-and-wife clown act, a depressive East European acrobat with a crush on Holden's character, a cynical soundman called Erasmus (Tony Robinson) and the self-seeking Welsh dame who does a performing-dog routine. Oh, and it's written by Daniel Peak, who wrote Not Going Out, so there's a bit of pedigree there. Lot of running gags, lot of slapstick, comedy of types. Think Dad's Army with red noses and spandex tights. And then, one guesses - since it's not very often these days that sitcoms get green-lit without jumping through this particular hoop - there would have been a rehearsed reading of the script, so that a collection of executives could mull over its prospects. And it's at this point that speculation hits an obstacle. How could they sit in the presence of gags this lame and character depiction this arbitrary and not say no?

It does go out at 7.30pm, so it's possible that the younger audience will be advanced as an alibi. It seems heartless to use children as a human shield in this way though, and surely they deserve better than gags about ferrets down trousers and punch lines that audibly creak as they're winched into place. "I was so worried that you'd fail us on the raw sewage round the hot-dog stand," blurted out Lizzie when the health and safety inspector gave her the all clear, a line that not even Helen Mirren could have made psychologically plausible. And without an underlying psychological plausibility (the urgent cartoon drives that you'll always find in Hi-De-Hi! and Dad's Army if you dig deep enough) it just isn't comic. That line isn't an inadvertent revelation - it's hopelessly, mechanically advertant, only there to be funny. In the end, an exchange between Plonky the clown and Erasmus offered the best verdict: "If we're so terrible why do we get a big cheer when we finish?" "I think you've answered your own question there."

Suddenly it's like the 1970s all over again, at least in TV sitcom land. If it's not Miranda gurning to camera and tripping over her giant feet, then it's Amanda Holden in fishnet tights and John Thomson shoving ferrets down his trousers. Which, sadly, is not a scene from a retro fetish club night but what passes for comedy on the fantastically rubbish Big Top.

The Office must have seemed another lifetime to Patrick Baladi when he found himself stranded amid the spit and sawdust as a health and safety officer in a circus sitcom so old-school it made Last Of The Summer Wine look raw and edgy. Assigned to the unenviable task of romancing Holden's dull ring mistress - think school ma'am on a hen night - Baladi was confronted by a box of dog poo. No, seriously, that was the punch line of the best joke of the night.

It was the once mighty Gladys of Hi-de-hi (aka Ruth Madoc) who was proffering the said turd, which made you feel for the talent being frittered away all round the ring. Sophie Thompson is a talented comic actress, but she has an unhappy knack of ending up in total turkeys and she's picked another one here as Thomson's clueless co-clown.

It was as though The League of Gentlemen had never happened. You can squeeze laughs out of clowns without resorting to abusing furry animals - the consistently excellent Modern Family had a great running gag about coulrophobia last week - but Big Top isn't anywhere near that league. The title isn't even a joke: it might have worked if Jordan was playing the lead but as it is it's just plain lazy. Another tent-peg in the coffin of the British sitcom (it's got so bad, I've even started laughing at Miranda. But that's probably the medication).

TV ratings: Big Top draws 3.3 million

BBC1's Amanda Holden sitcom launches against strong ITV1 opposition.

Big Top, BBC One, review

A review of the first episode of new BBC comedy Big Top. Big Top is so determinedly old-fashioned that if it were a person it would be wearing plus fours.

If we're terrible, why do people cheer when we finish?

Whoever it was in the commissioning department at the BBC who ok'd this show needs a slap.

Amanda Holden stars as a ringmaster in this Daniel Peak-scripted, circus-based sitcom whose impressive cast also includes John Thomson, Tony Robinson and Ruth "Hi-De-Hi!" Madoc. There are so few primetime sitcoms nowadays that the experience of watching one feels surreally olde worlde - the easily tickled audience who giggle like loons even at the straight lines, foreign accents regarded as inherently amusing and jokes about a ferret down a clown's trousers "having a ball". It's almost in Mitchell and Webb's Send for Hennimore territory - like a precise pastiche of bad British comedy.

Reports of the death of the British sitcom have been greatly exaggerated. With Last of the Summer Wine making its 31st series, My Family its 11th and even Reggie Perrin recommissioned, somebody's watching. And they're the same viewers likely to warm to this new family-friendly sitcom set in a two-bit provincial circus.

It stars Amanda Holden as ringmaster Lizzie, who struggles to control a gaggle of fading acts, including a wacky ageing performer (Hi-De-Hi!'s Ruth Madoc) and a pair of hopeless clowns (John Thomson and Sophie Thompson). The script by relative newcomer Daniel Peak features dog-napping plots and ferrets-down-trousers gags rather than the observational humour that's so hip these days, but it draws upon the rich tradition of earlier comedies - from Dad's Army to Steptoe and Son - in which the humour often came from characters who are compelled by their situation to do peculiar, funny things. Spirited performances by a decent cast go some way toward making up for the dated set-up. Baldrick himself, Blackadder's Tony Robinson, turns up as the circus's wisecracking accounts man, and Holden propels the action (she was, after all, a perky comic actress in Kiss Me Kate and The Grimleys before Britain's Got Talent and Botox took over). Launching any new sitcom is a bit of a highwire act, but audiences may roll up to this one.