School reunions are mercifully redundant these days.

We can stay in touch with people through social media instead. If you want to see how successful someone's become, just check their LinkedIn profile. If you want to see how popular they are, look at Twitter. If you want to see how tedious, check their Facebook baby pictures. Thanks to social media we need no longer congregate in the school gym and sway to Come On, Eileen. Reunions are so passe.

When a band reunites, there'll always be a hardcore of fans who're overjoyed, but everyone else may feel mildly uncomfortable. Them again? They were good in their day, but that one's fat now, and didn't the other one get arrested for that thing?

Wouldn't it be better to just remember them as they were? It's sad to see heroes of your youth reunite because they so often do it for reasons which reveal the depth to which they've fallen: they're bored playing in dingy seaside towns, or they're fed-up living silently in a bungalow, only emerging to perhaps do panto in Bexhill-on-Sea. It's awful to see them cluster on stage, tubby and slowed. They want to snatch back a bit of the old pep and pizzazz, but the era in which they shone has passed, the fashion and the clamour which sustained them has dwindled. They can't recreate it. 'You can't go home again'.

Morrissey, who used that quote in his Suedehead video, has typically acerbic opinions on whether The Smiths might reunite, as did George Harrison with The Beatles. He said there'd be no reunion as long as John Lennon remained dead.

So, as a Monty Python fan, I winced on hearing they intended to reunite and would play 10 shows at London's 02.

The Pythons had always insisted they'd never reform, so what changed their minds? Money, said Eric Idle. He says 'an idiot producer' of The Holy Grail had spent years suing them. They had a business meeting to tot up their losses and someone jokingly said 'if we did a night at the O2 we'd pay it off in a second.' So they set up such a night. It sold out in 45 seconds, and so they added more - ten in total - and will play to 150,000 people.

They're in it for the money, then, not for any sad clutching at old glory, and I respect them for that. Anyway, they don't need to pine for old successes as each one of the surviving team has gone on to great things: John Cleese with Fawlty Towers and A Fish Called Wanda, and who's currently touring the world with the show, 'Alimony', to pay for his divorce. He jokes that it could be worse: think how much he'd have to pay if his ex-wife had contributed anything to the relationship! Michael Palin has his well-loved travel shows, both the Terrys are film directors and Eric Idle has the musical Spamalot and a sunny Hollywood existence.

So they're in it for the money and that kind of in-your-face honesty is an echo of their manic comedy. You get the feeling, especially with the weirder Flying Circus sketches, that they're writing to make themselves laugh and if you don't get the joke then you can just go away and watch something else.

And it was this frantic, surreal comedy which was the highlight of the show. Alan Yentob goes on a jaunt across the world, from windy Yorkshire to sweltering Singapore to sunny LA to track them all down, interviewing them about the upcoming reunion. Despite his efforts, the best part of the one hour and 15 minutes was the occasional clips from the Flying Circus or the films. Like the most annoying Monty Python fan, I'd watch one of the short clips - the one about the Five Yorkshiremen, for instance - then would start laughing and quoting it and doing the accents and wanting to click straight onto YouTube to find the whole sketch. But then I'd remember I was a TV critic and so had to stay and watch the programme. But it was difficult to pay heed to Alan Yentob's sombre questioning of Terry Jones about the distribution of one of his films when my head was still ringing from laughter at the clips: Say no more! Hello polly! Nine out of ten British housewives can't tell the difference between Whizzo butter and a dead crab! Yes, the show's subject matter was so good I constantly wanted to interrupt it.

Python nuts will be miffed that an entire hour passed before there was any real reference to Graham Chapman, but it was heart-warming to see the team plan to include him in the stage show by inserting clips of him saying, 'Stop that! This is silly!'

This programme was a delight for Python fans but also as a survey of a bunch of odd, charmed, eccentric gentlemen who illuminated - and mocked - dreary, uptight Britain.

My only complaint was that the programme was too long. It could easily have been shortened without losing its impact. Maybe this is because of the paucity of arts coverage on the BBC: when they do give us something they want us to gorge on it as we'll get precious little else. There were several flabby, directionless scenes, especially where Eric Idle was involved. We spent an especially long time watching him poke around in his garage looking for the infamous bird from the Albatross sketch. This is where we certainly needed Chapman to stride onscreen, saying 'Stop that! This is silly!'