The research also found that just over one in ten (11%) think they may have been a passenger with a drug driver. At the same time, three in 10 (29%) admit they wouldn't always speak out to stop a friend driving on drugs and a significant one in 20 (5%) wouldn't speak out even if their friend was clearly out of control. This was most common among young (9%) and male (7%) drivers.

Young people and men are also most likely to have possibly or definitely been a passenger with a driver on drugs. 18% of young drivers and 15% of male drivers say they have been in this situation in the past year.

The findings come shortly before a new law, coming into force on 2 March 2015, will make it an offence to drive with drugs in your body across Britain, aiming to make it much easier to prosecute drivers on drugs.

Rob Miles, director of car insurance at Direct Line, commented: ‘Drugs and driving are a deadly combination which can have devastating effects on people's lives, particularly in combination with alcohol. Driving under the influence of illegal drugs seriously compromises someone's ability to control a vehicle, affecting their judgement, their reactions and their ability to concentrate. Direct Line welcomes the drug drive law coming into force next March and hopes it will act as a deterrent to anyone tempted to drive after having taken illegal drugs.’