Just 16% of drivers have stopped using their mobile phones at the wheel since a law change in March saw penalties for the offence doubled.

The RAC identified what it calls a ‘hard core of persistent offenders’ of more than nine million drivers, who believe they won’t face consequences.

The Report on Motoring 2017 questioned 1,727 drivers – a year after the previous report revealed a serious mobile phone problem on UK roads.

Among the habitual users, four in 10 are aged between 25 and 44, while 57.3% are men.

Even though the number making or receiving calls has dropped to 23%, from 31% last year, a total of 15% admit the change has made little or no difference to how they view the offence.

RAC road safety spokesman Pete Williams said: "It is clear we have a hard core of persistent offenders who believe they can get away with it by continuing to flout the law every day and we fear this may get worse with fewer dedicated roads policing officers.

"Drivers need to take more responsibility when they get behind the steering wheel and think seriously about whether choosing to pick up a handheld mobile phone is really worth the risk.

"We had hoped concern about drivers talking or texting at the wheel on their handheld phone would decline as a result of the Government taking the decision to increase penalties with fewer drivers breaking the law but this has not been the case.”

Around 11%, or 4.4 million drivers, are still not aware the penalty for being caught using a phone behind the wheel increased to £200 and six penalty points.

Despite the changes, a seemingly persistent 9.2 million drivers ignore the law on a regular basis.