However, because of the highly specific interests of most of the passengers, this did not present too much of a problem. The German word, Umwelt, meaning 'perceptual world', describes the priority given to various senses reaching animals' brains. The Umwelt of a dog is dominated by its sense of smell; a dolpin's Umwelt is dominated by echolocation. An American tourist's Umwelt is dominated by Andrew Lloyd Webber: no piece of information has any significance unless it relates to the Great Maestro.
Hence, as our bus turned around at the Aldwych, the guide made up for the lack of celebrities by chatting about which of the theatres had ever hosted a Webber production.
It turned out that our guide, Jane, an elegant, Rada-trained magician's wife, was the real star. She had a genuine talent for the transatlantic slant.
'On our right is Bush House, home of the BBC World Service, which broadcast the cricket scores to our hostages in Beirut.' This surreal introduction proved to be a dummy, setting them up for: 'And on our left is the Adelphi, where some of you may have seen Phantom.' The coach tilted in the rush to photograph the theatre.
We drove past Buckingham Palace, where Jane described how she'd once been to a Royal garden party. 'I shouldn't really say this,' she cooed conspiratorially, 'everyone was more excited by the special guests than by the Queen - Richard Burton and Elizabeth Taylor.' There was a collective gasp of admiration. She obviously had a map of North American erogenous zones.
Entering Belgravia, Mrs Thatcher's house is pointed out. The Duke of Westminster gave her the lease for pounds 10,000 (presumably the smallest number he could think of), a reduction of about pounds 7,990,000.
Then the big one. We drive into a square where the houses are obscured by trees. We slow down and park. One of the houses is the actual house of Sir Andrew Lloyd Webber.
In the clamour of clicking and flashing, we barely hear that he paid the full pounds 8m in the boom, and his lease is now worth only half that. 'Never mind, I expect he likes living there,' Jane reassures us.
We see Michael Caine's flat in the distance and learn that Roger Moore lives close to the address Ian Fleming gave James Bond. We also visit Freddy Mercury's shrine.
Going round Sloane Square, we get a marvellous introduction to 'the Sloanes. These are people from country families who come to London to work in art galleries, and group around the Square. They often get their clothes in Peter Jones.'
This falls on deaf ears. 'And this is the Royal Court Theatre, where some of our greatest playwrights had their early works performed.' Again, no response, until she mentions one 'who went on to direct Andrew Lloyd Webber's . . .', and I couldn't hear the rest above the clicking of shutters.
Golden Tours' Celebrity Tour, every Wed, Victoria Tourist Information Centre (071-409 0969) pounds 12.50