Haggle if you want cheaper black cab

Passengers are to be allowed to haggle with drivers to minimise the effect of soaring taxi fares.

A rule is being introduced which will let customers agree a price before they set off, rather than having to pay the amount on the meter.

It will come into force from April - when black cab fares are expected to rise by almost six per cent. This will be the sixth time the fares have risen since Ken Livingstone became Mayor in 2000. Transport for London is changing the rules after an Office of Fair Trading ruling last year that the amount on the meter should be a "maximum" rather than a "mandatory" charge.

This is to protect customers from being overcharged - while giving them the opportunity to negotiate the fare down.

TfL said the move was a step forward for passengers but warned it may have little effect in practice. "The Public Carriage Office doesn't see this happening," a spokeswoman admitted. "The likelihood is negotiating just wouldn't happen because the taxi driver would drive off."

Trade representatives poured scorn on the idea. Bob Oddy of the Licensed Taxi Drivers' Association said: "As a general rule, passengers don't want to barter with taxi drivers. Sometimes one or two passengers will say, 'I have missed my last train, I have only got ?30

on me, is that enough to get me home?' That is the sort of thing that has always happened. This rule will make no difference."

The change will be introduced on 2 April alongside the annual rise in black cab fares. Rates will increase by

3.5 per cent but the minimum fare will also rise by 20p to ?2.20, leading to an overall increase of 5.6 per cent.

According to TfL, the average fare will rise by 53p to ?9.91. It says there are 88 million black cab journeys a year. The rises will not affect minicabs. The 20p will be a "green" levy to help taxis comply with new air quality regulations.

A typical three-mile weekday journey will have jumped 60p to ?7.60 in just over a year, while a six-mile trip at the weekend will cost ?19.60 - ?1.60 more than last March.

The Liberal Democrats warned continued fare rises could put passengers' safety in jeopardy by forcing them to turn to cheaper illegal minicabs. They said the higher taxi fares completed a series of above-inflation rises imposed by the Mayor across all public transport since he was re-elected last June.

Bus fares rose by 13 per cent and Tube fares four per cent this month. Lynne Featherstone, Lib-Dem chairwoman of the London Assembly transport committee, said: "It seems no transport is safe from Ken Livingstone trying to bleed more cash out of Londoners.

"I am seriously concerned that allowing fares to rise even further could lead to more people using unlicensed minicabs, because they are considered the cheapest form of transport to get home on a late night."

TfL said the fare rises were set to ensure London's 25,000 cabbies received a cost-of-living increase and were compensated for rising fuel and maintenance bills.