With talks on a post-Brexit trade set to begin within weeks, Mrs May is to target an ambitious goal of reaching a deal “covering more sectors and co-operating more fully than any Free Trade Agreement anywhere in the world today”.
However, the commitment to the Union risks stoking a growing row with Brussels over the future of Northern Ireland, which threatens to set negotiations back to square one.
Speaking in London today, the Prime Minister will insist the UK’s Brexit deal can deliver on the pledge she made on entering Downing Street to “forge a bold new positive role for ourselves in the world” and build a country “that works not for a privileged few, but for every one of us”.
Mrs May will set five tests for upcoming talks on the second phase of Brexit in order to deliver on that ambition, starting with a commitment that the deal must “respect the result of the referendum” and honour the demand to “take control of our borders, laws and money”.
The Prime Minister will say the deal should mean “wider change” so that “no community in Britain would ever be left behind again”, while any deal with the EU “must endure” so that London and Brussels do not find themselves “back at the negotiating table because things have broken down”.
A third test will commit to “protect people’s jobs and security” despite warnings from within government that none of the available options can prevent a decline in economic growth.
The Brexit deal “must be consistent with the kind of country we want to be as we leave: a modern, open, outward-looking, tolerant, European democracy,” the Prime Minister will say.
“In doing all of these things, it must strengthen our union of nations and our union of people. We must bring our country back together, taking into account the views of everyone who cares about this issue, from both sides of the debate. As Prime Minister it is my duty to represent all of our United Kingdom, England, Scotland, Wales and Northern Ireland.”
Yesterday Mrs May was given a stark warning that her Brexit red lines will inevitably cause friction in trade between the UK and EU as both sides dug in over the future status of Northern Ireland.
The Prime Minister met the European Council president in Downing Street, with Donald Tusk criticising the UK Government’s red lines, saying: “I’m not happy.”
In Brussels on Wednesday night, Mr Tusk said: “There can be no frictionless trade outside of the customs union and the single market. Friction is an inevitable side-effect of Brexit by nature.”
The Prime Minister strongly rejected parts of a draft legal text of the withdrawal agreement produced by the European Commission regarding the status of Northern Ireland, which she said would “threaten the constitutional integrity of the UK” by creating a border down the Irish Sea.
Mr Tusk insisted all 27 EU members backed the draft and said the UK government’s decision to rule out membership of the single market and customs union meant “one of the possible negative consequences... is a hard border on the island of Ireland”.
At a special meeting of cabinet in 10 Downing Street, ministers were given 30 minutes to read the latest draft of Mrs May’s speech before a two-hour discussion.
With the cabinet having agreed to a strategy of ‘ambitious managed diversion’ from EU regulations after Brexit, Mrs May will commit the UK to be a “champion of free trade based on high standards”.