Only occasionally is Gavin and Stacey, the comedy about a girl from Barry who has fallen in love with a boy from Billericay, pee-yourself funny; the rest of the time it is soapy and sentimental. So why do I love it? I used to think it was because the genius of the few gags that it does offer, and the perfect performances put in by its cast, somehow gave me permission to wallow in - or to ignore - its saccharine plot; that, and how weary I am of brittle TV irony.
But it's more complicated than that. The series is just so completely itself; it has integrity, its own internal rules. I like its elliptical qualities: the way that some things (Nessa's tall stories, Bryn's sexuality) are never explained or commented on, and the way that characters take shocking or kinky goings-on (an unexpected pregnancy, a threesome) in their stride, but then make stern judgements about daft things like whether or not a hotel is changing the sheets every day.
On the subject of sheets, the changing of, a good test, in the opinion of Gavin's mum, Pam (Alison Steadman), is to hide two wine gums in a pillowcase: if they are still there when you come back from your hot stone massage, you'll know what's what. Pam, in her approach to this and other aspects of Essex life, has a certain loopy intensity that she shares with Bryn (Rob Brydon), Stacey's uncle, and Smithy (James Corden), Gavin's best friend.
They are all desperately loving, which makes them sweetly vulnerable even when they're being monstrous; they fear, dreadfully, being excluded from Gavin and Stacey's newly-wed bubble. There are people like this in all extended families - except, perhaps, not quite like this. Gavin and Stacey returned from their honeymoon to a banner at the airport ("We missed you and love you so much," Pam had written in magic marker); to a sulk about three weeks of unreturned calls (Smithy's); and to an uncle who'd had a T-shirt printed in advance, so excited was he by the prospect of their homecoming.
In the end, Smithy was calmed by Gavin's profferring of a dubious bottle of alcohol. The fact that they'd once seen this booze in Nuts magazine - you got the feeling that Smithy wouldn't have been bothered, otherwise - is symptomatic of how well-written the series is. Corden and his co-writer, Ruth Jones, know when characters should stay silent (after a rabbity monologue by Bryn, usually) and when they should add the crucial detail.
They are also deft at what you might call stagecraft. The new series began with a double bill, and the first show was mostly involved with getting all the characters in one place again: Bryn and Nessa had come south with Stacey's stuff, which, it later turned out, included a giant cuddly giraffe (house-proud Pam looked at this piece of inert wildlife, and jigged anxiously in her designer wellies). The writers weren't content, however, with assembling everyone in Pam's house; they crammed everyone in the loo at an Italian restaurant where Pam's friend Dawn (Julia Davis) was sobbing at the premature demise of the threesome she'd organised on the internet - a farce that could not have been wrapped up more expertly had it been written by Michael Frayn. Levers were pulled, but silently as the night.
The second part was funnier, though. Pregnant Nessa (Ruth Jones) claimed that "Richard" had offered her a place to stay, only "Judy" wouldn't have it, on account of the fact that, in the old days when she was the couple's nanny, she and he would spend whole days making love. Cue a kind of long-suffering but not wholly sceptical silence from Pam and Stacey. All the plot strands are now in place - Stacey's homesickness, Smithy's discovery of his impending fatherhood - to enable the rest of the series to unfold without too much contrivance. I can't wait to see what happens.
I suppose this is the real magic of it: Gavin and Stacey isn't just a comedy show, each episode quarantined from the last. These are characters whose destinies you care about. You want them to be happy and never to stop being so very kind and loving.
Pick of the week
The No 1 Ladies’ Detective Agency
23 March, 9pm, BBC1
Adaptation of the Alexander McCall Smith novel set in Botswana.
Starts 23 March, 11.45pm, Channel 4
Straight out of suburbia comes a new series of the US comedy.
The Curse of Comedy: Hancock and Joan
26 March, 9pm, BBC4
Series of dramas about comedy icons continues, with Tony up next.