Brexit secretary David Davis hailed the promised document to come next month as “our most significant publication on the EU since the referendum”.
Aides have indicated it will cover future trade, financial services regulation and clearly establish the UK’s position on the vexed issue at the heart of withdrawal negotiations – future customs relations.
The paper is an attempt to get on the front foot in Brussels amid fears that EU negotiators too often set the agenda, to reassure Tory MPs that Ms May has a coherent plan and give civil servants a framework upon which to take decisions.
But it comes amid deadlock in cabinet over customs relations, stalemate in parliament in efforts to pass Brexit legislation and claims from the EU that no progress has been made in negotiations since March.
The prime minister confirmed to her cabinet on Tuesday that that the government is producing the white paper on its proposed future relationship with the EU.
Mr Davis told the meeting: “This will be our most significant publication on the EU since the referendum.
“It will communicate our ambition for the UK’s future relationship with the EU, in the context of our vision for the UK’s future role in the world.”
He went on to tell senior ministers that it is “an opportunity to set out clearly to both a domestic and an EU audience the reasoning behind our approach, including where we think it is clearly in the EU’s interests as well as our own”.
The document will “include detailed, ambitious and precise explanations of our positions … it should set out what will change and what will feel different outside the EU”.
The Independent understands that officials have been tasked to wrap a broad array of issues into the document, such as future dispute settlement, cooperation with EU bodies, the security partnership, law enforcement and defence and foreign policy.
It will also cover digital and broadcasting issues, science, transport and energy and the aims of the future UK/EU economic partnership, taking in the Britain’s services sectors, financial regulation, goods, agricultural, food and fisheries products.
Critically, it will also look at customs arrangements – despite British cabinet ministers still being split down the middle over whether to diverge from the EU’s customs union or opt for closer arrangements.
Another meeting of the cabinet’s Brexit subcommittee ended on Tuesday without ministers agreeing to a clear plan on which of Ms May’s two options on customs relations to adopt.
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Sources told The Independent that working groups set up to study each the options were yet to do any detailed work on developing them in a bid to find a cabinet compromise, with efforts to now focussing on the process they will follow to reach a consensus.
While ministers have not been given a timeframe in which to come to a mutual agreement on customs, the emergence of the white paper next month indicates they will have to make progress in the coming weeks.
On Sunday Ms May wrote a piece for The Sunday Times asking for voters to “trust” her to get a good deal for Brexit.
The day after she held a string of meetings with Tory backbenchers to try and assure them progress is being made.
But insiders say the white paper is also about trying to grease the wheels of Whitehall, with decisions on Brexit related issues taking a long time and other matters being held up due to broader uncertainty.
It is hoped that the document will give civil servants a clear framework upon which to take decisions across a range of policy areas, allowing the processes of government to begin moving more freely.
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It comes as Labour launched a new bid to force the government to release details of its proposals for post-Brexit customs arrangements and the Irish border.
Jeremy Corbyn’s party tabled a motion in the Commons for debate on Wednesday, which if passed would require the government to release to parliament all papers prepared for the Brexit subcommittee on Ms May’s two options: a “customs partnership”, with closer EU customs ties to avoid an Irish hard border; or “max fac”, with looser customs ties, but a harder border.
It is the latest in a string of Labour motions using an arcane parliamentary procedure to make the vote binding on the government by issuing a “humble address” to the Queen asking her to require ministers to comply.