Motorists who adhere to speed limits are often bullied by aggressive drivers trying to force them to speed up.

Following drivers will tailgate in an attempt to force the other motorist to go faster, a new study has found.

The evidence from research into driver behaviour carried out by TRL – the Transport Research Laboratory – and Direct Line Insurance showed a fourfold increase in tailgating incidents when motorists were driving at the maximum legal limit.

The observational study monitored the response of other drivers to motorists driving to the letter of the law.

It found that 93% of the motorists were tailgated by other road users when driving in accordance to the Highway Code.

The study also revealed that 40% of drivers following the Highway Code were either over or undertaken by other motorists.

The study showed raised heart rates by these drivers when tailgated, suggesting that many drivers become stressed and emotionally upset as a result.

“Causes for tailgating may be ascribed to a number of factors, from drivers being unaware of their own unsafe driving behaviour, to frustration with the lead vehicle for driving at the national speed limit and is therefore an attempt to speed them up,” said Dr Nick Reed, senior human factors researcher, TRL.

“It’s also possible the current two-second rule could be encouraging it, as many drivers may find other cars pulling in between them and the car in front when leaving a two second gap.

"This in turn, may cause frustration and discourages drivers to keep their distance.”

During the 15 hours of monitored drives whilst following the Highway Code, the study also recorded six instances of direct conflict with other road users.