Taken for a ride by guides

Just after we had sat down for our trip a microphone crackled into life, the aged speakers squealed, and a voice one could only describe as Cockney wide-boy announced: "Er, yeah, all right, do you want me to give you a commentary then?" A few of us shouted: "Yes!" and that seemed to be all the encouragement required.

"Yeah, all right then. Er, I'm not actually an official tour guide, I'm a crew member but I will give you this guide to make your journey more enjoyable," our indulgent host declared as the craft began to chug upstream. "On yer right, you'll see Waterguard House, and that's the 'ome of the Customs and Excise. Story goes that it's three times deeper underground than above. That's where they are supposed to destroy all the illegal drugs and goods they find. They say the Christmas parties there last about two weeks."

Passengers stared at each other, baffled by our guide's informal style. A few giggles rippled around the boat. "A bit furver on, and there you'll see a big glass building that we on the crew think was built by an out-of-work window cleaner - apparently 'e was named Luigi the Squeegee.

"On yer left there's the Golden Hind, Sir Francis Drake's boat, well worf a visit. In front you'll see Cannon Street Bridge. Lovely old Victorian bridge. You'll see that they have built some modern offices in between the pillars and [deeply ironic tone] you can see how they made 'em blend lovely.

"Comin' up is Southwark Bridge and there's quite a funny story abaht this as it goes. The architect hid all the approach roads to it so it's quite rare to see it this busy.

"On yer left, there's Shakespeare's Globe, built by Zoe Wannamaker's dad who yer may have heard of. Well worf a visit.

"That brick monstrosity on yer left wiv an old chimney sticking up, that's an old power station. Spent a lotta Lottery money on it and now its an art gallery, Tate Modern. Well worf a visit.

"Comin' up you'll see the Millennium Bridge. Opened on the 7th of June, closed on the 8th of June. It was a complete disaster and its now called the wibbly-wobbly bridge. On yer left, that tower is home of LWT. Each Friday they take over our TV and serve us up with all those repeats. LWT tower - Last Week's Television.

"That large concrete monstrosity on the left is the Royal Festival Hall. There on the left is the London Eye. They say it's doing pretty well. Well worf a visit.

"On yer left is County Hall. It used to be the 'ome of the GLC until it was abolished by our old mate, Maggie Fatcher.

"As I said, lay-deez and gennlemen, I'm not paid for this, but if you would like to show your appreciation, I'll be leavin' a large bucket by the gangplank on the way out. 'Ope you enjoyed it."

VERDICT: This is the real London, shown to you by a really cynical Londoner. Fantastic entertainment, and our guide's collection bucket overflowed with £1 coins.

Tour 3: walking tour. Rock'n'Roll London

Our guide was Ian. There were five of us in our group, and the tour, planned to last an hour and a half, began on Haymarket.

First stop was the Prince of Wales Theatre. Ian, obviously used to larger groups, shouted very loudly: "The Beatles performed here, when the Queen and Queen Mother were watching. John Lennon said to the crowd, 'We need a little help with this one. Those of you in the cheap seats clap your hands, those in the expensive seats rattle your jewellery', and looked up at the where the Queen was sitting. That was typical of him."

I sighed inwardly. It was going to be a long 90 minutes.

We made our way to Old Compton Street, the place where, Ian informed us, "our gay community meet and have drinks and er, what have you..." On Frith Street we paused outside Ronnie Scott's. Ian has a good story here about how Jimi Hendrix was in the crowd watching the Animals and the band invited him on stage. He agreed, played a few numbers and left. That was the night he died.

We walked on down Broadwick Street "which was on the cover of the Oasis album, Morning Glory", and stop outside the public lavatories. "Peter Cook and Dudley Moore were denied entry to the Ad-Lib club, so they came to this toilet and started the Ad Lav club. John Lennon came down and 'opened' it for them."

It was all too awful. I made my excuses and left 30 minutes early.

VERDICT: The tour comprises walking and standing around outside buildings. Nothing really to see.

Tour 4: The Frog

The Frog is a refurbished 1942 amphibious vehicle which took part in the Normandy landings. Our guide was James, our driver was Danny. On board was a party of Scottish schoolchildren.

We set off from behind County Hall, drove across Westminster Bridge and into Parliament Square. We headed towards Trafalgar Square, where our guide informed us that every year "half a ton of pigeon poo" has to be cleaned up.

At St James's, our guide pointed out White's Club. "That's where Prince Charles likes to go for a beer and a game of darts." He jokes: "It's also where he had his stag party and met Camilla - she was the gorillagram that night.

"Straight ahead of us you can see a wall. That is the Queen's back garden. If you look over you may see her out mountain biking - although today is Wednesday and that's skateboarding day.

"You see the big spikes on the walls? That's to keep people out. A few years ago, a German broke in and fell asleep in the grounds. It was very embarrassing. Willie Whitelaw, who was in charge of the Queen's security, said: "It will never happen again.

"Two weeks later, the Queen woke up in the night to see the shadowy figure of a man in her room. She said, 'Philip, how ever did you manage to get past security?'" We crossed the river again, past the MI6 building where the James Bond connection is explained. We pulled up in front of a slipway and there was much shifting of levers to prepare for our descent on to the Thames. We headed down the slipway at 30 mph and the Scottish kids screamed. With a splash, we were on the river.

"Welcome to the River Thames. It's long, and it's wet and it's affected by the tide. It's not dirty or smelly, that's just me and Danny. It is home to over 100 species of fish - you often see them floating on the surface with their distinctive three eyes. There is the London Eye. It's 400ft high, and from the top you can see 13 bridges, seven football stadiums, and my house. It's the one just behind the kebab shop."

We sidled up to the Houses of Parliament. "You can see writing in Latin along the walls. That is the Lord's Prayer. It's supposed to keep the evil spirits out, but strangely enough 659 of them keep getting back in.

"On the left you can see a very tall building with a penthouse at the top. That is the house of Jeffrey Archer. He is famous for stories of sleaze and political scandal - and the other day I found out he is a writer too." James continued in a similar vein as we left the Thames and went back to where we started.

VERDICT: The most fun we had all day. The kids loved driving into the Thames at high speed. Oh, okay - I did too.