Prime Minister David Cameron has promised to introduce roadside drug testing following a weekly newspaper’s campaign.

The Croydon Advertiser joined forces with the family of 14-year-old Lillian Groves to launch Lillian’s Law after the teenager was knocked down and killed by a driver who was high on cannabis.

This week reporter Gareth Davies visited 10 Downing Street with members of Lillian’s family to meet David Cameron who has now given his explicit backing to the campaign.

He revealed the Government plans to change road safety legislation making it illegal to drive under the influence of drugs beyond a certain limit.

Mr Cameron also said Lillian’s Law made a ‘strong argument’ for a zero-tolerance approach which would see drivers lose their licence if caught with any illegal substance in their blood, regardless of the level.

And the Prime Minister promised a “big shunt” to get breathalyser-like devices in every police station as fast as possible.

He told the newspaper: “There’s a lot of different drugs they are trying to test for and I think you have to evaluate what works.

“But the intention of Lillian’s Law, and I think where the Government is going, is that it should be done now.

“It’s just like the breathalyser really. It’s incredibly simple and should be in every police car.

“I admit it’s taken too long. We’re going to give it a big shunt and get them into police stations as fast as possible because I think that will make a difference.”

The PM went on to tell the family and Advertiser that the current law on drug-driving is ‘all wrong’ and admitted successive Governments had taken ‘too long’ to introduce road-side testing equipment, the primary goal of the Lillian’s Law campaign.

The front page of the Advertiser this week

When he left the specially arranged meeting he promised Lillian’s family he would not let them down.

As the meeting was on the same day as the storming by protestors of the UK Embassy in Tehran, the PM arrived to the meeting slightly late and out-of-breath, declaring ‘Sorry to keep you waiting, our embassy in Tehran has been stormed by an angry mob.’

Said Gareth: “To be sat in Number 10 discussing changing the law with the Prime Minister was quite a surreal experience. I got the impression he genuinely accepts the Government needs to take drug-driving more seriously.

“But we’re not getting carried away. There’s still have a long way to go and if the meeting lacked anything it was concrete information about when these changes will be enforced.

“To be fair, it was also good of Mr Cameron to see us, given how clearly busy he was.”

Advertiser editor Glenn Ebrey said this was the most ambitious newspaper campaign he had ever been involved in.

Said Glenn: “Because of that, its outcome also makes it the most satisfying.

“Gareth and Lillian’s family have worked tirelessly to raise awareness of the need to take drug-driving more seriously and their efforts have been rewarded in the best possible way. Reaching the Prime Minister with our message is about as good as it gets for a newspaper campaign.

“The next step is to make sure that Mr Cameron is true to his word and looks to enforce a change in the law. We will be keeping a very close eye on the situation to make sure he stays true to his promise.”