Boris takes on May by giving his vision for a ‘glorious’ Brexit in which £350m extra a week WILL be spent on NHS

BORIS JOHNSON last night told Theresa May to forget paying vast sums to the EU after 2019 - insisting the cash be spent on the NHS instead.

In a huge challenge to the PM's authority, the Foreign Secretary mapped out his vision of a "glorious" future for Brexit Britain.

And he said we must slash payments to Brussels as soon as we leave.

He insisted the Government had to make good the Vote Leave campaign pledge to increase spending on the NHS by £350 million a week.

He added that remaining in the single market or customs union after Brexit would make a "complete mockery" of the Referendum.

The revelation comes exactly one week to the day before Theresa May is set to map out her vision for Brexit in Florence, Italy and will send shockwaves through Westminster.

Reports yesterday the PM will use the speech to offer to maintain our annual £10 billion-a-year payments to Brussels during a two or three year ‘transition’ phase with the EU.

A transition or ‘bridging’ phase would ensure Britain maintains close-to-existing relationships with the EU between Brexit and the date at which a new trade deal comes into force.

But today's column by James Forysth reveals the Foreign Secretary is against spending billions even during the interim period. On well-placed Tory said: " 'If you're paying for access, you haven't left yet' is - I'm told - his view.

"He can't possibly stomach this. The PM has to be very careful."

Fellow Brexit backer, the Environment Secretary Michael Gove, is also pushing for more money to go on the health service.

Boris Johnson's intervention - on the day of a bomb in London - risks backfiring.

But it highlights growing tension between the "Leavers" and the Cabinet and those who were on the "Remain" side who believe a transition phase is critical to protecting the economy until a new trade deal with the EU can be ironed out.

One senior Tory lifted the lid on the tensions yesterday by criticising the lack of consultation over the Government’s strategy.

The Tory said: “It’s all being kept very tight among the PM and the ‘kitchen cabinet’ of Remainers – Damian Green, Amber Rudd and Philip Hammond.”

The bitter row risks dominating the run-up to the Prime Minister’s big Brexit speech in Florence next week.

Theresa May is expected to map out her vision of Britain’s future relationship with Europe and stamp her authority on the divorce talks.

Because of Brexit, the EU faces near £30 billion hole in the EU Budget between 2019 and 2022. And a senior EU official yesterday said transition would come at a price.

The official said: “Obviously should there be a transition … there is a contribution to make for that single market participation which is independent and on top of any debts from the past.”

The PM’s former chief of staff Nick Timothy said he believed the PM would be wrong to make “too great a concession”.

He tweeted: “The Europeans are unlikely to respond to a single speech, however generous, with sudden and dramatic movement.

“And if the PM tried to force the pace by making too great a concession, she would risk giving away too much too soon.”

He said: “The speech can however point the way to making sufficient progress on the departure agreement, which in turn can allow talks on future relationship to begin.

“The Florence speech will be important but we shouldn’t expect too much.