Road safety charity Brake has today called for a zero tolerance approach when it comes to drinking and driving this Christmas, as a survey reveals a shockingly casual attitude towards it among some young drivers.

A survey co-published by Brake and Direct Line insurance has found that almost one in three (29 percent) are planning on driving after having a drink, while perhaps more dangerously, more than half (53 percent) say they'll get behind the wheel the morning after a major Yuletide drinking binge.

The survey has also revealed that one in eight believes that they can drink three units or more and still drive safely, within the limit.

It's difficult to put a figure on the number of units a person can drink while remaining under the limit, because a number of factors affect a person's blood alcohol level, including their weight and tolerance to alcohol.

As a rough guide, a large glass of wine (250ml) will contain around three units.

The UK's drink driving limit is 80mg per 100ml of blood - the highest in Europe. Brake is calling for a 20mg limit, which would effectively be a zero tolerance approach, allowing some leeway for someone that, for example, has eaten food made with a small amount of alcohol.

The good news from the UK's young drivers (those aged between 17 and 24) is that significantly fewer are admitting to driving after drinking than were a few years ago: in 2007, 44 percent said they had, while in 2011, 29 percent did. That's a lower figure than the percentage of older drivers that today admit to driving after drinking - 36 percent.

In 2010, 250 people were killed and 1,230 seriously injured by someone that was drink driving, with thousands more by those with a legal level of alcohol in their system.

Brake's advice this Christmas, aside from the obvious 'don't drink and drive', is to plan ahead to make sure you're never in a situation in which you're expected to get into a car with a driver who's had a drink. You should also, Brake says, speak up against someone who's about to drink drive.

Direct Line's Tom Woolgrove said: "Alcohol and driving do not mix. There is no excuse. Young drivers may feel pressurised when on a night out with friends to have a few drinks and still get behind the wheel. However, the consequences can be devastating for them, their passengers or innocent road users."