Smoking ban in cars carrying children 'by 2015'
A ban on smoking in cars carrying children in England will come into force before the next general election, which is due in 2015, No 10 has said.
Ministers plan to act on last night's vote "sooner rather than later", sources have told the BBC, suggesting legislation could be introduced in the forthcoming Queen's Speech.
They added "the details have to be worked through".
But those who flout the ban could face fines and points on their licences.
The vote - passed by 376 votes to 107 - gave ministers in England and Wales the power to bring in a ban - but does not compel them to do so.
The Welsh government must now decide if they want to make smoking in cars carrying children illegal in Wales.
An amendment to the Children and Families Bill paving the way for a ban was introduced by Labour members of the House of the Lords, which backed it by 222 votes to 197 - despite opposition from the government.
Ministers had argued that the new law was a "blunt instrument" and public information campaigns were preferable.
But the government subsequently introduced its own "more workable" version of the amendment in the Lords, announcing that its MPs would have a free vote on whether to overturn the move in the Commons - meaning that they were able to vote with their consciences, free of pressure from party officials.
The British Medical Association (BMA), which has campaigned for a ban since 2011, said the vote was an "important step forward in reducing tobacco harm".
Dr Penny Woods, chief executive of the British Lung Foundation, said: "The introduction of a law that would help prevent hundreds of thousands of children from being exposed to second-hand smoke in the car is now within reach.
"With both Houses of Parliament having made their support for the ban clear, the onus is now on the government to act accordingly and make this crucial child protection measure law at the earliest opportunity."
Analysis of voting lists revealed divisions in the cabinet over the matter.
Health Secretary Jeremy Hunt, Chancellor George Osborne, Chief Secretary to the Treasury Danny Alexander, Defence Secretary Philip Hammond, Education Secretary Michael Gove, International Development Secretary Justine Greening, Scotland Secretary Alistair Carmichael and Energy Secretary Ed Davey all voted in favour of the ban.
But Justice Secretary Chris Grayling, Home Secretary Theresa May, Work and Pensions Secretary Iain Duncan Smith and Northern Ireland Secretary Theresa Villiers opposed it.
PM David Cameron missed the vote while visiting flood-stricken areas in south-west England.
His official spokesman declined to say which way the prime minister would have voted had he been able to attend, but he told reporters: "While he understands the concerns that some have expressed, his view is that the time for this kind of approach has come."
Following the Commons vote, a Welsh government official said: "We have consistently stated that we will consider the possibility of legislation once we have fully evaluated the impact of the campaign.
"We have commissioned studies of children's exposure to second-hand smoke in cars and results will be available later this year."
In Scotland, Liberal Democrat MSP Jim Hume has indicated he will be presenting a bill this year to bring in a ban, while Northern Ireland's health minister has announced plans for a consultation on the issue.
AA president Edmund King said: "As has been the case with enforcing the ban on hand-held phones while driving, campaigns and legislation have been shown to reduce illegal behaviour afterwards.
"If a new law manages to make more adults think twice before lighting up with the kids on board, it will have helped."
But pro-smoking groups described the move as an "unnecessary intrusion".
Simon Clark, director of the smokers' group Forest, said he was "disappointed but not surprised" by the vote and accused the government of being "spineless".