The Weekend's TV: What a load of jailhouse schlock

Louis Theroux: Behind Bars, BBC2; Lark Rise to Candleford, BBC1; Jamie's Fowl Dinners, Channel 4

Naivety has always been an important tool for Louis Theroux, a presenter who regularly pretends to know far less than he actually does in order to coax his subjects into spelling things out. All reporters have to do this sometimes, simply to get the necessary words out of the horse's mouth, but in Theroux's case the wide-eyed innocence is part of the brand too, along with that faintly nerdy walk and the startled remarks ("Really?!") when some nutjob says precisely what everyone had predicted he would when the production team was drawing up a filming schedule. This calculated innocence has proved rather useful in the past, staving off affront and even physical assault from interviewees who teeter precariously on the ledge of self-restraint. But that it can have its drawbacks was illustrated by Louis Theroux: Behind Bars, in which Louis spent two weeks in San Quentin prison, a kind of battery farm for human miscreants.

The first thing Louis's guide did was to issue him with a stab vest, just in case an inmate became so outraged by this guileless Englishman that he decided to shank him. In fact, most of them seemed reasonably pleased to be interviewed, either because anything that broke the routine was to be welcomed or because they relished the opportunity to boast about their crimes. Trophy inmate in this regard was David Silver, a violent sociopath who had clearly been brought to Louis's attention as one of the prison's landmark attractions. "First, I've got to do 521 years," he replied when Louis asked him how long he was in for, "... and then 11 life sentences." Hardly worth scratching lines on your cell wall, really. David talked to people such as Prince Charles, with his hands behind his back, because he'd got so used to them being handcuffed into that position.

Theroux's film was full of such details, including a nifty telecommunications device that I'd never seen in any prison movie before, which involved slingshotting a weight on a piece of string up and down the line of cells. "Are they allowed to do that?" asked Louis in a bemused tone, as the message box shuttled back and forwards in front of him, a rare instance of the question in your head coinciding with the one being asked on screen.

All too often, though, Theroux's studied cluelessness was obstructive rather than helpful. At one point, he sat down in the canteen with a group of white supremacists called the Barbarian Brotherhood, who politely explained how they would administer a beating to anyone who fraternised with black prisoners. "It was hard to believe they could be so brutal about something so trivial," Theroux said on the commentary. Don't you watch any television, Louis? Wasn't the name Barbarian Brotherhood a clue? And if you'd spent less time pretending to be baffled perhaps you'd have noticed that in the background white and black prisoners were sitting together, and asked a more searching question about how far the Brotherhood's writ actually ran.

Elsewhere, Louis pretended that he didn't know why prisoners might wish to have a transgendered hotty billeted in their cell ("What for?" echoed the man he was talking to with genuine incredulity. "Hull-low!") and, a touch offensively, I thought, asked whether San Quentin might be regarded as an all-you-can eat buffet by its gay inmates: "You sort of have your pick of hundreds of men... is there a case for saying it's quite a good place for you to be?" His interviewee, with remarkable restraint, didn't attempt to stab him with a sharpened toothbrush.

Cranford and Candleford. There's only a handful of letters between them but, oh, the difference to me. I can't quite work out why, really. Both dramas draw on the comedy of rural snobbery, the poignancy of constrained affections and the consternation of village politics. They even share a flutter of excitement over the new fabrics in the local drapers. But whereas Cranford felt convincingly layered, you get the sense that everyone's just pretending in Lark Rise to Candleford, laying on the bucolic twee in great bucketfuls. There is a terrifying quantity of accordion music and a lot of general "arring" and "garring" from the characterful locals. A lot of people will love it, and I wish them all happiness, but it reminded me of one of those toasters with ears of barley printed on the side of it.

On Friday, Jamie's Fowl Dinners had given a far less romanticised view of rural industry today, including the on-screen gassing of little fluffy male chicks, unprofitable and therefore destined to be "depleted". We learnt about other euphemisms, too, including "the value sector" (chickens with rickets and ammonia burns) and "wet eggs" (a kind of watery soup of battery-farmed eggs that gets added to a huge range of processed foods). It was (along with the Hugh Fearnley-Whittingstall programmes that preceded it) absolutely exemplary public-service television: interesting, informative and unhysterical in its presentation of the facts.