You might not be attracted by the idea of a 90-minute documentary about teenage geeks obsessed with mathematics, but Beautiful Young Minds (BBC2) turned out to be fascinating. It followed some of the young people hoping to be chosen for the British team for the International Mathematical Olympiad and watched them training at 'mathematics camps' and enduring numerous exams to test their suitability.

Maths has changed a lot since I was at school (whatever happened to addition, subtraction, multiplication and division?). The participants talked knowingly about such mysteries as vertices, circumradii, complex numbers and field theory. But the programme was more about the people than the mathematics.

Several of the contestants were autistic, which apparently gives them valuable powers of concentration. Yet their maths ability as well as their autism sets them apart from other people, and they find themselves ostracised by their peers at school and awkward in social situations.

Jos seemed entirely emotionless, answering the interviewer's questions with deadpan logic and addressing everyone as if he was an encyclopedia. Daniel was more likeable: modest and unassuming. He felt most at home when he visited China, where his eccentricity could be interpreted simply as the awkwardness of a British visitor. He was so shy that he couldn't bear to collect the medal he eventually won at the Olympiad. It was heart-warming to see him happily marrying his Chinese girlfriend - and also to see that the overbearing Jos didn't get into the final team.

The Nature of Britain (BBC1 and BBC2) is supposed to be heart-warming but it is actually chilling to encounter yet another BBC documentary series in which a celebrity stomps around Britain telling us how beautiful it is. In this case the presenter is Alan Titchmarsh (who has already presented British Isles - A Natural History). He may know about plants but he's unlikely to know much about the animals he enthuses about. Perhaps that's why his commentary sounds as if he is reciting a script written by somebody else. Still, he adds platitudes of his own, like "Sometimes it seems as though it never stops raining in Britain".

The BBC is so short of money that it is having to make massive staff cuts, yet it must still be paying large sums of money to people like Titchmarsh, when they could get a real expert for a tenth of the price.

In Bremner, Bird & Fortune (Channel 4), Rory Bremner did a nice parody of Titchmarsh saying things like "Have you noticed how lovely Britain is?", filmed in a studio against back-projected scenery to point up the artificiality of it all. The South Bank Show (ITV1) interviewed John Bird and John Fortune to elicit some of the secrets behind their "Two Johns" sketches, which are an integral part of the Bremner show. They get together for two hours every morning, four days a week, and discuss ideas for their duologues, which pierce through the mendacity and stupidity of politicians, civil servants, businessmen and other deserving targets.

Bird and Fortune work together almost telepathically, which is not surprising as they have been best friends since they met at Cambridge in the late 1950s and worked together at the Establishment club and on various TV programmes. For The South Bank Show, the two Johns performed a sketch about short-sighted bankers which, with commendable prescience, was prepared before the Northern Rock troubles.

d=3,3,1Now here's a funny thing. It's a new channel strangely named Dave which was launched this week on freeview although, like most freeview channels, it consists basically of old repeats. It appears to be aimed at males between the ages of 16 and 35 but you may still find it worth exploring, as it includes some worthwhile programmes like QI and the British version of Whose Line Is It Anyway? (preferable to the US brand with its unbearably raucous audience). It also offers one of the best-written and best-acted old sitcoms - Coupling, albeit at around 2.15am.