The spokesperson for European Council President Donald Tusk, Preben Aamann tweeted: "@eucopresident meets PM @theresa_may today at 16h on #Brexit" and Tusk is reported to have cancelled a trip to the Middle East where he was to Palestinian Prime Minister Rami Hamdallah in Ramallah and Israeli Prime Minister Benjamin Netanyahu in Jerusalem.

The "critical moment" in question suggests a breakthrough on the so-called "divorce bill" and the UK-EU border in Ireland has seen sufficient progress to move on to talks on trade in mid-December.

An EU spokesman told Express.co.uk the "state of play of Brexit negotiations" would be discussed during Mr Tusk's meeting with Mrs May this afternoon, the spokesman confirmed that the pair would not be releasing press statements after the meeting "for the moment," before declining to release any further details about what was to be discussed.

Before Mr Tusk meeting with Prime Minister May, his schedule has been hastily rearranged to include a veritable whos-who of Europe's most senior deep-state finance figures.

This morning Mr Tusk met with Klaus Regling, Managing Director of the European Stability Mechanism - a permanent firewall for the eurozone, to safeguard and provide instant access to financial assistance programmes for member states of the eurozone in financial difficulty, with a maximum lending capacity of €500 billion.

Mr Tusk then met with Eurogroup President Jeroen Dijsselbloem, the Eurogroup comprising of the finance ministers of EU states of the European currently using the euro as their official currency.

While Mrs May and negotiator David Davis talk with European Commission President Jean-Claude Juncker and his Brexit negotiator, Michel Barnier, at 12.15 (GMT), Mr Tusk will meet with President of the European Central Bank Mario Draghi.

At the meeting that will presumably make or break Britain's hope for trade talks later in the month, Tusk has scheduled a 4pm meeting with UK Prime Minister Theresa May.

What is concerning for those hoping for a fair and positive outcome on Brexit progress is the shifting opinions held by those bureaucrats in discussion with Mr Tusk before his meeting with Mrs May.

While Mr Dijsselbloem has been very vocal in unsettling City of London firms and claiming that Brexit will spur finance exodus from City, Mr Draghi has recently taken a more reasonable line, saying back in March: "We haven't seen yet a consequence" or a "significant economic impact from Brexit, despite the ECB's expectations".

Prime Minister Theresa May’s spokesman said on Monday that there was more still to be agreed upon between Britain and the European Union in Brexit negotiations, although good progress is being made.

“As we’ve always said about today, good progress is being made, there’s more still to agree upon,” the spokesman told reporters ahead of a meeting between May and top EU officials in Brussels.