The study, conducted in West London, indicated that those who drive a “Chelsea tractor” were nearly four times as likely to use a hand-held mobile phone while on the move, and significantly less likely to use their seatbelts, as were drivers of more commonplace cars. Although neither of these is a hanging offence, the result will be come as no surprise to other road-users who dislike 4x4s.

Two researchers from Imperial College and one from Australia decided to test whether driving in a large, high and muscular vehicle such as a 4x4 made motorists feel that they were immune to danger.

According to the “risk compensation” theory of behaviour, people are happy with a certain level of risk. Official attempts to reduce it — by enforcing rules on seatbelts, for example — tend to be compensated for by more risky driving, nullifying the benefit.

Big cars are safer (for the people who drive them, at least) than small ones; a fact which has been publicised by the Department for Transport.

So Konrad Jamrozik, now at the University of Queensland, and Lesley Walker and Jonathan Williams, from Imperial College, set out to test the theory by observing whether 4x4 drivers were more likely to flout the law. They picked three areas in Hammersmith, West London, in which to conduct their experiment, and, on five successive weekdays, watched vehicles passing for an hour in the morning, an hour in the afternoon and an hour in the evening.

They ignored taxis, buses and white vans, concentrating on ordinary passenger cars and 4x4s.

They observed more than 38,000 normal cars and almost 3,000 4x4s. They found that almost four times as many drivers of the 4x4s used their mobile phones on the move. They were also 26 per cent more likely to leave seatbelts unfastened.

Drivers who committed one of these offences were also more likely to be committing the other, indicating a persistent behaviour trait.

One suggested reason was that the drivers of four-wheel-drive vehicles, which cost more than the average car, were more likely to be mobile phone users — but, the authors say, mobile phones have become so cheap that almost every driver has one.

The results, reported in the British Medical Journal, show “a worryingly high level of non-compliance with laws on seatbelts and hand-held mobile phones by drivers in London”, the team concludes. Almost one in six drivers was not wearing a seatbelt.

“The theory of risk compensation predicts that drivers of four-wheel-drive vehicles take more risks when driving. Our findings strongly support this hypothesis,” the authors say. “Greater efforts are needed to educate the public and enforce these laws. Although four-wheel-drive vehicles are safer in a crash, their owners may be placing themselves and other road users at increased risk of injury.”

Four-wheel-drive vehicles have become so unpopular among other road users that a group dedicated to banning them, the Alliance Against Urban 4x4s, has been created. Hayley Rolfe, a spokeswoman for the group, said: “Too many people are driving a dangerous weapon through our crowded streets because they regard it as a fashion accessory. Our aim is to make driving these things socially unacceptable.”

Owners of 4x4s have also attracted the ire of Ken Livingstone, the Mayor of London, who has described parents who drive them to the school gates as “complete idiots”.