Last Night's Television: Inside John Lewis, BBC2<br />Timeshift: Bread - a loaf affair, BBC4

Anyone with a passion for cobnuts needs to keep an eye on the Freeview spin-off channels these days. Cobnuts – for those of you who missed last week's entertaining documentary about Rachel Johnson's attempts to revamp The Lady magazine – was the nickname she gave to the idiosyncratic articles that were a feature of the organ she inherited, which included such urgent topics as the history of the cucumber and the virtues of the cobnut (hence the name). Rachel didn't much care for cobnuts and tried to get rid of them, only to discover that her audience had a strong affection for pieces with no rationale but their own curiosity. Cobnuts aren't generated by someone's publicity agenda or trying to ride a wave in the zeitgeist or piggy-backing on a celebrity pronouncement. They're just there because interest coagulated to create them.

Timeshift: Bread – a Loaf Affair was a classic cobnut, packed with cobnutty-type people, who'd devoted their lives to one passion, and could happily pick the bits out of a wholemeal loaf all day, discussing the provenance of the flour and the exact nature of its milling. It had a vague reason for existence in the shape of BBC4's run of food-themed programmes, but you got the feeling that wasn't a necessary pre-condition for its existence. And, for anyone who likes a good cobnut now and then, it was a treat, even allowing for its passion for terrible puns. If you'd thought that the one in the title was going to be the worst of it, you were wrong. There was a pun in their choice of narrator (Tom Baker) and some absolute horrors in the script he had to read, including a line about "diverting the kids from the path of whiteousness", which actually rendered me unconscious for a couple of seconds.

The justification for that last crime against language was the essential tale that Bread – a Loaf Affair told – the eventful marriage of class-consciousness and bread-styles. In the medieval period, white bread was an exclusive luxury, the great mass of the peasantry making do with loaves that were only just distinguishable from the millstones that ground the wheat that went into them. So bakers did their best to fake a white loaf for the mass market, adultering their flour with chalk dust and alum. The arrival of Canadian and American wheat and the invention of the roller mill enabled them to deliver a product, which didn't actually poison their customers, at which point, naturally, the upper crust decided that it was time to shift back to brown loaves. Hovis – invented by a Mr Smith, aimed itself squarely at the aspiring middle classes, but by now the flour required to make such bread was more expensive than the refined white stuff, so the working class once again got stuck with loaves that weren't quite what they purported to be. And then Mr Allinson came along and started marketing "wholemeal", which complicated matters still further.

There were jolly bits of archive from the Seventies, showing the rise of industrial white bread and the wholefood fightback, there was a positively erotic sequence in which someone baked a ciabatta loaf and there were a string of those savoury little facts that all cobnuts contain – social implication rising up from them like the steam from a freshly baked loaf. Take the fact, for instance, that it was illegal to sell the National Loaf – a one-flavour fits all product of war-time rationing – until it was a day old, a kind of rationing by staleness that helped contribute to the immense popularity of white flannel bread in the Sixties and Seventies. Curiously, this cobnut also concluded on a highly topical note. South African society is now replicating almost exactly the powerful (and nutritionally damaging) association between arctic white bread and social sophistication.

In a hundred years' time somebody will make a cobnut about the great shift to online retailing, though presumably it will take the form of a synaptic download or 2110's equivalent of a streaming Twitter feed. Inside John Lewis concluded with the opening of the Cardiff store (Welsh choir, carnations all round, barely restrained hysteria among local yummy-mummies) and the continuing development of John Lewis's online shop, which has now branched into fashion. It also included a little section on that cheeky advertising campaign, which suggested that people took advantage of John Lewis's expert customer care and advice and then bought the goods they'd selected from Dixons instead. The John Lewis people got a bit flustered and cross when that came out, presumably forgetting that their consternation and anxiety was at that very moment contributing to the kind of advert that no amount of money could buy for Dixons, a three-part series on BBC2 that represented John Lewis as the wholemeal loaf of the retailing world, full of the goodness that some bakers leave out.