Christmas shoppers are being offered voluntary breath tests as part of a campaign to remind drivers of the dangers of drink-driving.
Shoppers will be able to find out if it is suitable for them to drive
The Met is inviting members of the public to take the test to see if they would be over the limit to drive that evening or the following morning.
Traffic officers will be in shopping centres and train stations handing out leaflets on drink-driving dangers.
The Met is also tackling binge-drivers guilty of drunken misbehaviour.
'Think before drinking'
Acting Ch Supt Ian Chappell said: "Lots of people enjoy a drink or two over the Christmas and New Year period but we need people to think before they drink.
"Think about how they will get home and whether they need to drive the following morning."
He said the campaign will also aim to ensure that people know about the penalties of drink-driving.
"Not only can you receive six months in prison, a £5000 fine and a 12-month ban, but you could also take somebody's father, daughter or husband away from this Christmas," he said.
Anti-drink drive patrols will also be stepped up at locations known to have a higher rate of collisions and on main routes in to and out of town centres.
If drivers are suspected of driving while over the alcohol limit they will be required to take a breath test.