The UK has already “agreed in principle” to a Norway-style Brexit transition period in which it accepts all EU rules with no power to shape them, a senior figure in Brussels has told The Independent.

A key member of the European Parliament’s Brexit team said British negotiators raised no objections to the plans, which would mean accepting free movement and customs union rules, and falling under the European Court’s jurisdiction.

The suggestion that Theresa May’s team has all but swallowed the transition proposal from Brussels will anger Conservative MPs, who believe it leaves Britain a “vassal state” for some two years after Brexit.

Data from a survey of Tory MPs on Monday suggested three-quarters oppose a transition in which free movement for EU citizens continues.

A government source told The Independent that while Ms May has set out a desire to achieve a transition or “implementation” period on “current terms”, exactly how it will work has not been decided.

Belgian MEP Philippe Lamberts said that the UK is going along with proposals that mean after Brexit in March 2019, Britain will continue as a member of the EU in “all but name” until at least December 2020.

Brexit: the deciders Show all 8 1 /8 Brexit: the deciders Brexit: the deciders European Union's chief Brexit negotiator, Michel Barnier Getty Brexit: the deciders French President Emmanuel Macron Getty Brexit: the deciders German Chancellor Angela Merkel Reuters Brexit: the deciders Commission President Jean-Claude Juncker EPA Brexit: the deciders The European Parliament's chief Brexit negotiator Guy Verhofstadt Getty Brexit: the deciders Britain's Prime Minister Theresa May Getty Images Brexit: the deciders Britain's Chancellor of the Exchequer, Philip Hammond PA Brexit: the deciders After the first and second appointed Brexit secretaries resigned (David Davis and Dominic Raab respectively), Stephen Barclay is currently heading up the position PA

During that period, the UK would have full access to the single market, adhere to free movement rules and those of the customs union and follow edicts from the European Court of Justice.

The UK would also continue to pay into the EU budget, but will not have any voting rights or a seat at the European Council – a situation akin to Norway’s current relationship with the EU.

Mr Lamberts, who sits on the cross-party Brexit steering group, said discussions about the transition deal had taken place and at no point in meetings he was in had British Government officials disputed proposals for the Norway-style transition.

“During the transition period, the UK will be a member in all but name, but it will no longer sit at the two tables where decisions are made; parliament and council,” Mr Lamberts told The Independent.

“It has to be a Norwegian-style deal, it cannot be anything else and this has been agreed in principle.”

He added: “I heard no one disputing this from the UK’s side.”

EU trade deal after Brexit like trying to ‘blow up a bridge without bankrupting yourself’, warns negotiator Cristophe Bondy

The six MEPs on the Brexit steering group coordinate and prepare the European Parliament’s strategy on the UK’s withdrawal, has regular meetings with chief EU negotiator Michel Barnier and has attended some meetings involving British officials.

Elmar Brok, who also sits on the group, echoed Mr Lamberts comments and described the transition period as being a “Norwegian agreement for a limited time”.

It has to be a Norwegian style deal, it cannot be anything else and this has been agreed in principle Belgian MEP Philippe Lamberts

Adding that the European Parliament would release a statement on it in March, he said: “We are on the way to making the official proposal, it will outline that it should be like a Norway deal.

“This is the position of all three institutions.”

Gabriele Zimmer, a German MEP on the group, also said that during the transition period the UK was expected to fulfil all its obligations but would have no say in decision-making.

EU preparations for a ‘no deal’ Brexit are “damaging” UK interests, according to David Davis

She added that if the UK crashes out of Europe without a deal, there would be no transition period at all.

“There is no guarantee there will be a transition period. I have the feeling that the British Government thinks it has more time to negotiate, but the transition is not guaranteed,” Ms Zimmer told The Independent.

“If we have no deal, there will be no transition period.”

The length of the transition is still yet to be confirmed but, as the EU budgetary year is from January to December, unless Britain is willing to commit to payments for an entire year it is most likely it will come to an end in December of 2020.

Elmar Brok sits on the European Parliament’s steering group (Getty)

Danuta Hubner, a Polish MEP on the steering group, confirmed the length of the transition is dependent on Britain’s financial contributions.

“If Britain does not want to pay, then on 1 January 2021, they should be gone from the EU in the sense of benefiting from what transition gives,” she told The Independent.

In her keynote speech in Florence, Ms May said that “during the implementation period access to one another’s markets should continue on current terms and Britain also should continue to take part in existing security measures”.

A government source said details of how the transition will operate including in relation to critical areas such as the customs union and immigration are still subject to negotiations.

A Brexit department spokesperson also echoed Ms May’s remarks in response to the MEPs’ comments, saying: “The UK is looking to agree, by March, a time-limited implementation period on current terms, meaning there will be just one set of changes for businesses to manage.

Brexit: Philip Hammond signals 'status quo' will remain two years after withdrawal

“But we will no longer be an EU member state, the EU treaties will no longer apply and we will have left the single market and the customs union.”

Yet despite the stated position, Chancellor Philip Hammond was attacked by Tory Brexiteers when he said in a speech last year that the UK was minded to go along with EU plans that would “effectively replicate the current status quo”.

At the time, Conservative MP Jacob Rees-Mogg suggested the plans would end up with the UK effectively becoming a “vassal state” of the EU.

Former cabinet minister John Redwood MP told The Independent on Monday: “You can’t possibly agree anything until you know the whole thing – what you are transitioning to.

David Davis: UK can have 'Canada plus plus plus' trade deal with the EU after Brexit

“There’s no reason you should accept giving them all the money, accepting rules and courts unless there’s something at the end that Britain wants.”

Ipsos Mori interviewed 105 MPs in private, face to face, with the findings weighted to reflect the composition of the House of Commons.