At 10.30 on Wednesday morning the sunny front of the Bank of England is furiously busy with men in combat trousers, leather jackets and old trainers, carrying suspiciously heavy rucksacks. They are purposeful and menacing. They’ve come a long way for this; they’ve come to show the world a thing or two. They are the media.

“We are the media and we won’t be moved! We are the Albanian Early Evening News!” They stand around complaining that demos aren’t what they used to be. A Turkish photographer tells a Japanese reporter that if you want a good riot you need to be in Athens, Switzerland wasn’t bad, Canada was surprisingly eventful, but what you really needed for a gas, fire and water truncheon party were Kurds. You can’t beat the Kurds. Or rather, you can’t beat them enough.

Fifteen minutes later the mood is turning ugly. There are no demonstrators. They’re late. Then, bit by bit at Liverpool Street station, one of the four starting points for the mass attack on the mother of all banks, an emetic trickle of what appear to be public school pupils on half-term arrive. They hang around waiting for something to happen, apparently unaware that they are what’s supposed to be happening.

The look is Die-Hard-meets-emo: faded grey jeans as tight as surgical stockings, Converse trainers, big hoodies, T-shirts advertising retro bands rather than actual convictions and scarves. Scarves are all-important. There are still some Palestinian keffiyehs, but frankly they’re a bit passé. Much better are the knock-off Alexander McQueen scarves with the black and white skulls. The skull is the 21st century’s ban the bomb sign, a perfect, omni-cultural symbol for groovy activism: a bit Damien, a bit ironic Motörhead, a bit ecological and nuclear, a bit Natural History Museum.

There are a surprising number of nubile girls in carefully chosen Angelina Jolie-style urban street gear, terrorists with lipgloss and Brazilians: a look that yet again proves the illogical truth that the more ridiculous, unsustainable and plain otherworldly the politics are, the more likely they are to attract really hot totty.

Then there are the inevitable method demonstrators. Marches, movements and marathons attract men who can’t resist the weirder exuberances of the dressing-up box, handfuls of Merlins, devils, monsters, an American soldier from Apocalypse Now with eyeliner, giant bunny outfits and quite a lot of men in suits. As all the bankers in the City have been told to dress down and are consequently scuttling into work looking like the white van men so many of them are about to become, anyone in a suit on Wednesday is an anarcho-syndicalist from Stepney.

When a critical mass of about 1,500 has been achieved, we stroll towards the Bank, herded by double lines of police.

As we are ushered down Threadneedle Street there’s a noticeable absence of banners. There are a couple rhyming banker with wanker, frankly barely worth the effort of holding up, and a big one demanding “One currency, one country, one world”, which sounds like Alan Greenspan’s tattoo and is a brilliantly succinct description of globalisation. My favourite, after “Trannies against greed”, is a chap who has hand-written his own T-shirt. On the front it proclaims “I just sold my hedge fund” and on the back adds, “And all I got was this lousy T-shirt”.

The whole thing reminds me, rather warmly, of my own student days in the 1970s. Precious little has changed. We could have been standing around to end the Vietnam war. The one noticeable difference is that whenever the moment of bargy turns argy, everyone pulls out a camera or a phone. It gives the demonstration a strangely voyeuristic turn like a political version of dogging. This is not an event, merely the rough cut, to become real when edited and twittered and blogged and YouTubed later on.

I get a call that says it’s all kicking off round the corner: “They’ve arrested the giant bunny.” The police cordon closes in to practise the ancient Metropolitan tactic of crowd control by bladder control: after four hours of pelvic clenching, Tank Girl activists will be reduced to promising, crosslegged, that they will never ever have another contrarian thought if they’re just allowed into the bogs at Starbucks.

I show the top lackey of the capitalist conspiracy my press pass. “Take your glasses off,” he says. “What’s the name on the card?” Well it’s mine of course. “Okay. You can go. Nice outfit.”

A few streets away on Bishopsgate it’s another world. I know it’s another world because there are lots of banners saying what we need is another world. One huge one says “Nature doesn’t do bailouts”. It seems to me nature has been doing nothing but bailing out for 10m years. This is the climate camp, a tented suburb of whimsy with Buddhists chanting meditations for peace, teachins, sit-ins, afternoon tea and quite a lot of snogging, scratching and nit-picking.

These are the young people who you’d be proud to have as children: committed, caring, visionary, smiley and moral without prudery. You just wouldn’t want to talk to them much, or share a towel. I bump into Emily Sheffield, deputy editor of Vogue. She's here with a photographer, an assistant and a picture editor. They’re doing a story on pretty eco-warriors. She tells me they were caught in that beastly cordon and the police wouldn’t let them out.

“I had to tell them I was pregnant and needed a drink and a pee. The policeman said I didn’t look pregnant so I showed him my tummy: ‘What do you think this is?’ ” It may look like a bun in the oven up at Vogue, but down at the Met it looks like another emaciated waif. In the end she asked if the policeman wanted to talk to the editor of Vogue: that did it.

A pretty girl offers to paint my face. After five minutes she says: “I’m really not very good at this.” Paris, for that was her name, was from Cheltenham Ladies’ College and is going up to Edinburgh to read social anthropology after a gap year teaching English in Tanzania.

In Trafalgar Square about 2,000 weary people listen to rote-rants on Palestine, Afghanistan and Iraq, although no one seems to have noticed that we have just pulled out of Iraq. The speakers are Bruce Kent, Tony Benn and Arthur Scargill. Shirley Williams is at the green camp. It is like Fleetwood Mac reuniting: nostalgic agitprop.

There are people selling Socialist Worker - still - and a stall manned by the Communist party of Great Britain (Marxist-Leninist). Capitalism, democracy, the free market and the global economy may have dropped the ball, but that’s nothing compared with the paucity of new thought coming from the radical left.

This was a feeble half-hearted semi-set trifle of a demonstration that didn’t have the shadow of an answer in its tousled balaclava’d head. To what conceivable crisis could the emergency response be Benn, Kent, Scargill, Williams, communism and a man in a giant bunny suit?

Times recommends

• Live chat: Thrifty ways to update your winter wardrobe
• Is anybody out there really listening?
• Nutrition Q&A: Will eating late make me fat?