London can't afford the great black cab rip-off

London cab fares are a scandal. When I'm in Paris, I use taxis and stare in disbelief at the meter, unable to believe how low the fare is compared with my own city. In Brussels not long ago, rushing from the European Parliament to catch the last train to London, I paid a fare that would have been reasonable in pounds, then realised it was in euros.

Just about everyone I know has horror stories about hailing a black cab after 10 o'clock at night and reeling out with next to no change from £25. Often you have to visit an ATM first to make sure you won't run out of cash; after a recent trip to a sold-out concert at the Albert Hall, I walked down to South Kensington Tube station and discovered that the District line had closed early, leaving thousands of people to start looking for money for taxis.

Most of my women friends long ago switched to using minicabs, although the standards required of drivers are lower than for black cabs. Many people feel uncomfortable with drivers who don't have a detailed knowledge of London. I've had minicab drivers lecture me on the benefits of sharia law and even ask me out, which is the last thing a woman wants from an unknown man who knows her home address.

Even a short journey across London by black cab during the day currently costs between £4.20 and £6.20, according to TfL's own figures - an astronomical amount of money to travel a single mile. And that's before April's 4.7 per cent fare increase, which will see the average cost of a taxi ride rise to just under £11. TfL says that's compared to a cost index which includes average national earnings, and the average fare will go up by only 2.7 per cent. But that's still above the Government's estimate of inflation.

What TfL can't dispute is the enormous disparity between the cost of taxis in London and comparable cities in other countries. In New York, a sixmile journey after 8pm costs around £8. In Paris it's £9 and in Brussels - a city full of people on expense accounts if ever there was one - it's around £10. In London, according to TfL's own figures, you can expect to pay between £18 and £22. After 10pm, when black cabs switch to their highest tariff, it's between £21 and £24.

Why the difference? The usual reason given is the high cost of buying a black cab, an argument that hinges on the unusually precise specifications demanded by the Public Carriage Office - notably turning circles, which are tighter for black cabs than for other vehicles of similar size - but I suspect that most Londoners care more about the level of fares than the need to avoid three-point turns. TfL says that the cost of fuel is higher in the UK, and that London regularly tops polls for offering the best taxi service in the world.

At the same time, it's undeniable that journeys are taking longer because of the Mayor's rephasing of traffic lights, leaving cabs to queue endlessly - and pump out pollution - at junctions where only a couple of vehicles get through each cycle.

TfL can't produce figures to show the impact of fare increases on patterns of use, which means that it doesn't actually know for certain whether the exorbitant cost is driving people to use other - and less safe - forms of transport. That means there's no way of assessing the real impact of raising fares at 10pm, which is when lone women are trying to get home and want to avoid drunks on the Tube and night buses.

The increase, which follows an earlier one which starts at 8pm, was introduced in 2001 to encourage more cab drivers to work late at night. "We want to make sure there are plenty of safe travel options in the evening," says a TfL spokeswoman, apparently unaware that you don't expand people's options by pricing them out of the market.

For most of us, it doesn't matter how many black cabs are on the streets in the evening if we can't afford to hail one. I also can't help wondering why London cabbies need such huge incentives to work at night when their counterparts in New York get by on a fare structure that pays around half for journeys of the same length. With a hotly contested mayoral election looming, I'm amazed that the question of black cab fares hasn't already become a big campaign issue.

Even if TfL doesn't have figures on the relationship between fare rises and taxi use, there is evidence from cabbies themselves that the public is losing patience. "Have we killed the golden goose?" asks an editorial in the February issue of Taxi Talk, reporting that cab drivers up and down the country had a terrible Christmas. It says that alarm bells are ringing throughout the trade after a sharp decline in custom on Christmas Eve, Boxing Day and New Year's Eve - "those three days when you could come out with a hand-cart and still make a killing".

It seems the taxi trade hasn't recovered from the millennium celebrations, when "the great British public voted with their feet, or rather their wallets, and stayed home in droves". Taxi Talk even asks whether it might be better to operate normal tariffs on bank holidays and get some passengers instead of having to "sit around most of the day".

This is a bleaker picture than that painted by the Mayor of London and TfL, neither of whom seems to have grasped the damage done to the reputation of this great city by the absence of a safe, affordable taxi service. Before that cab is lowered onto the plinth in Trafalgar Square, let's paint it gold in recognition of the fact that under Mayor Livingstone, black cabs have become a luxury.