Theresa May has warned her Cabinet gathered for Brexit talks at Chequers that the UK is at a “significant moment”, as she was told by an ex-minister that British businesses will not survive without EU free movement.

At the start of the meeting at her official country residence, the Prime Minister underlined that there would be “no attempts to sort of stay in the EU by the back door”.

But as she was delivering her message, former Business Minister Anna Soubry said UK growth was dependent on the free movement of EU citizens across UK borders.

Splits have also emerged within the cabinet itself with some ministers preferring a Brexit that leaves the UK inside the single market while others want to leave completely.

It comes amid speculation that Mrs May will trigger Article 50 of the Lisbon Treaty, starting formal Brexit talks, without first putting it to a vote of Parliament.

Mrs May has tasked each member of her cabinet to form a plan of how their department can capitalise on Brexit.

She told them at the start of the meeting: “We’ll be looking at the next steps that we need to take, and we’ll also be looking at the opportunities that are now open to us as we forge a new role for the UK in the world.

The 6 most important issues Theresa May needs to address Show all 6 1 /6 The 6 most important issues Theresa May needs to address The 6 most important issues Theresa May needs to address Brexit The big one. Theresa May has spoken publicly three times since declaring her intent to stand in the Tory Leadership race, and each time she has said, ‘Brexit means Brexit.’ It sounds resolute, but it is helpful to her that Brexit is a made up word with no real meaning. She has said there will be ‘no second referendum’ and no re-entry in to the EU via the back door. But she, like the Leave campaign of which she was not a member, has pointedly not said with any precision what she thinks Brexit means Reuters The 6 most important issues Theresa May needs to address General election This is very much one to keep off the to do list. She said last week there would be ‘no general election’ at this time of great instability. But there have already been calls for one from opposition parties. The Fixed Term Parliaments Act of 2010 makes it far more difficult to call a snap general election, a difficulty she will be in no rush to overcome. In the event of a victory for Leadsom, who was not popular with her own parliamentary colleagues, an election might have been required, but May has the overwhelming backing of the parliamentary party Getty The 6 most important issues Theresa May needs to address HS2 Macbeth has been quoted far too much in recent weeks, but it will be up to May to decide whether, with regard to the new high speed train link between London, Birmingham, the East Midlands and the north, ‘returning were as tedious as go o’er.’ Billions have already been spent. But the £55bn it will cost, at a bare minimum, must now be considered against the grim reality of significantly diminished public finances in the short to medium term at least. It is not scheduled to be completed until 2033, by which point it is not completely unreasonable to imagine a massive, driverless car-led transport revolution having rendered it redundant EPA The 6 most important issues Theresa May needs to address Heathrow expansion Or indeed Gatwick expansion. Or Boris Island, though that option is seems as finished as the man himself. The decision on where to expand aviation capacity in the south east has been delayed to the point of becoming a national embarrassment. A final decision was due in autumn. Whatever is decided, there will be vast opprobrium PA The 6 most important issues Theresa May needs to address Trident renewal David Cameron indicated two days ago that there will be a Commons vote on renewing Britain’s nuclear deterrent on July 18th, by which point we now know, Ms May will be Prime Minister. The Labour Party is, to put it mildly, divided on the issue. This will be an early opportunity to maximise their embarrassment, and return to Tory business as usual EPA The 6 most important issues Theresa May needs to address Scottish Independence Nicola Sturgeon and the SNP are in no doubt that the Brexit vote provides the opportunity for a second independence referendum, in which they can emerge victorious. The Scottish Parliament at Holyrood has the authority to call a second referendum, but Ms May and the British Parliament are by no means automatically compelled to accept the result. She could argue it was settled in 2014 AFP/Getty

“We must continue to be very clear that ‘Brexit means Brexit’, that we’re going to make a success of it.

“That means there’s no second referendum, no attempts to sort of stay in the EU by the back door, that we’re actually going to deliver on this.”

Philip Hammond is expected to put forward plans for a sector-by-sector approach to remaining in the single market at the meeting.

There is a desire among some ministers to agree access for the financial sector and the car industry, while at the same time curbing immigration.

But other senior ministers including Brexit Secretary David Davis and International Trade Secretary Liam Fox favour totally pulling out of the single market to gain full control of UK borders.

This morning Ms Soubry told the BBC such a move would damage the UK economy. Asked if she wanted to retain free movement, she said: “Yes, that is my view.

“I believe in the free movement of labour form the EU. It has benefitted our country, especially business.

She went on: “Go and talk to those businesses, whether it’s picking fruit, whether it is people relying on highly qualified engineers, other experts working in British business.

“British business could not survive without access to that free movement of labour.”

She urged colleagues to make a “good strong positive case” for immigration or risk damaging UK growth.

Mrs May is also expected to use the meeting as a show of Tory unity, comparing it to the current unrest in Labour during the party’s leadership contest.

In particular, it will be an opportunity for the three ministers who have a role in Brexit, Foreign Secretary Boris Johnson, Dr Fox and Mr Davis, to appear side by side.

Theresa May says she has an 'open mind' over Brexit negotiations

There have been reports of a turf war between the three cabinet members, as Dr Fox and Mr Davis attempt to build their departmental workforces up from scratch.

Downing Street has said MPs will be given "a say" on the process for the UK's departure from the EU.

But a Downing Street spokesman repeatedly declined to say whether Parliament would be given a formal vote on triggering Article 50.

Number 10 has insisted there is "no legal obligation" for Mrs May to consult Parliament before invoking the Article and has said it will not take place before the end of the year.