Twickenham MP Tania Mathias has said she will vote to trigger Article 50 this evening, effectively confirming Britain’s exit from the single market, despite the 2015 Conservative manifesto saying the party wanted to stay in it.

Dr Mathias, like many of her fellow MPs, will vote to begin the process of leaving the European Union this evening, after the debate on the Government's white paper.

EU leaders have said full access to the single market depends on countries accepting the free movement of people, as well as goods, capital and services.

Two weeks ago Prime Minister Theresa May said what the Government proposes for Brexit “cannot mean membership of the single market”.

The 2015 Tory manifesto read: “We say: yes to the single market. Yes to turbocharging free trade. Yes to working together where we are stronger together than alone.

“We benefit from the single market and do not want to stand in the way of the Eurozone resolving its difficulties.

“Indeed, given the trade between Britain and the Eurozone countries we want to see these economies returning to growth.”

Brexit supporters argue manifesto pledges regarding the single market have been overtaken by recent events such as the referendum result.

Dr Mathias supported the Remain campaign.

Dr Mathias, who was elected to parliament in May 2015, said she work to help Britain get the “best deal” from Brexit, and that she hoped the country would end up with “as much access as possible” to the single market.

She said: “We can push for the best deal through the committees and in the chamber. I want to get the best deal for Twickenham, and especially businesses in the constituency. I am confident for our businesses.

“In two years’ time when we are out of the EU we will, I hope, be having good access to the single market but details regarding that will be coming through.”

Neighbouring Richmond Park MP Sarah Olney said she will vote against the bill which would trigger Article 50.

Her Liberal Democrat party has said it will vote against triggering Article 50 until a second referendum, once the terms of Brexit have been announced, has been promised.

When asked whether this was undemocratic, given last year’s referendum returned a result in favour of leaving the EU by 52 per cent to 48, Mrs Olney said she had a “personal mandate” to hold the Government to account on the terms of Brexit.

She said: “I represent a constituency which voted very strongly in favour of remaining in the EU. I feel very strongly we should stay in the EU.

“I said I would do this in the by-election campaign, so I feel I have a mandate to vote this way.”

The Twickenham and Richmond Park constituencies voted 69 per cent and 72 per cent, respectively, in favour of remaining in the EU.