Last Night's TV: Dispatches: Sandwiches Unwrapped, Channel 4; Battle of the Brains, BBC 2

I was not entirely in tune with the premise of Alex Thomson's argument in Dispatches: Sandwiches Unwrapped. "I tend to think of sandwiches as pretty healthy," he declared. Which in any reasonable food-literate observer could only elicit the response: "Are you mad?" Sandwiches? Aren't they evil bread, smeared with evil butter, stuffed with evil cheese and garnished with evil chutney? Aren't they a well-known way of consuming at least 500 empty, over-priced calories, and still feeling hungry? Aren't they obesity-crisis in a ludicrous triangular box-thing?

Dispatches left no chill cabinet unexplored in its eagerness to explain to us that this was indeed the case. Yet the only shock was that sandwiches from Boots actually turned out to be nearly as wholesome as something you might make for yourself at home. I was astonished by this outlandish revelation. It was investigative journalism at its most challenging and shocking.

Pre-prepared food is one of the wonders of the modern world. You feel certain that there can be no soul left who does not know that, basically, it is all a seriously bad idea. Yet, clearly, people carry on buying it. The British sandwich industry is worth £5bn, even though, strictly speaking, there is no reason on earth why anyone at all might find the purchasing of a pre-made sandwich a necessity. You assume at least that people know they are throwing money away on rubbish, and do it anyway. Yet, time and again, that belief is entirely scuppered, as yet another television programme comes along and breathlessly reports, shock, horror, that some little corner of the industry has been placed under scrutiny, and, shock, horror, has come out wanting. Who, for example, would have imagined that the anaemic and ghastly offerings often to be found languishing in the less salubrious of petrol stations and corner shops were perfectly acceptable fare? Most people I know would be as likely to find themselves eating their own children as they would one of these.

It was therefore entirely unsurprising that the poor undercover reporter who got herself a job for a fortnight at an "independent" sandwich factory found that untrained staff worked for £2.50 an hour in conditions that were wholly unsanitary in order to make them. Gosh. Even though these unfortunate people manage to turn out food that looks exactly like something that might give you salmonella, it is still necessary to "expose" their obvious dreadfulness. What suckers we must be. Still, the programme did at least hint at what the "disconnect" between what we ought to know, and what we actually do, might be. It was painfully obvious that people really believe in the nanny state, and imagine a government whose tentacles reach into every corner of every life, checking, double-checking and laying down the law.

The sandwich in the service station might look really dodgy, but it's on sale, so the environmental-health chaps much have been down to give it the once-over. The sandwich in Pret a Manger might not have its ingredients written on the box, but it has signs up all over the shop insisting that our health is its "passion", and it wouldn't be allowed to say that if it wasn't true. And so on.

The food industry kicks and screams before every tiny hint of legislation that might hamper its cynicism. In one exchange, one of its representatives explained that it championed consumer choice, and therefore reserved the right to play fast and loose with voluntary Government targets on salt content.

Subway, however, doesn't offer much "choice". A total of 93 per cent of this highly successful chain's sandwiches contain a level of salt that is deemed, rightly, to be terribly unhealthy. But because the sandwiches are made on the premises, it doesn't have to ensure that the hapless consumer knows this, just that if they set out to do some internet research prior to popping into the shop, then they'd be able to find out. Or maybe they should just assume that the shop's products are no more healthy than they look, or taste. Just a thought.

Meanwhile, the quest to find a quiz show to rival Weakest Link goes on, this time in the form of Battle of the Brains. Quiz leagues across Britain have been scoured and last night's show featured two teams of stalwart purveyors of general knowledge, with a worrying number of the 12 contestants – in two teams – describing themselves and their lives through the agency of their pets. The format is rather good, and the pet-loving brain-boxes were bright and modestly charming. The host, though, is a mistake. A charisma-free zone called Paddy O'Connell was so uncomfortable with the sudden-death nature of the game he presided over, that he exclaimed at one point: "It's just so mean!" Paddy, Paddy, Paddy, that's the bit you're supposed to relish most, you dunce.

Brian Viner is away