No officials from the government were present, and sources said Whitehall civil servants were "raging" that they were not part of the discussions. The Prime Minister, Theresa May, risks being further undermined if Trump chooses to meet Tory Brexiteers privately when he visits the UK at the end of next week, as many in Westminster believe is likely. Britain's Prime Minister Theresa May during celebrations marking National Armed Forces Day in Llandudno, Wales, on Saturday June 30, 2018. Credit:AP News of the meeting comes just days before a crucial away-day meeting of the Cabinet at May's Chequers country retreat to finalise Britain's negotiating strategy and agree a new government white paper - to be published the following week - which will set Britain's course after Brexit. The Prime Minister was facing mounting pressure this weekend as:

• Dozens of Tory MPs and parliamentarians set out a series of Brexit red lines that May must not backslide on, including any continuation of freedom of movement or remaining part of the customs union; • Concern grows that David Davis, the Exiting the EU Secretary, could walk out after it emerged that briefing papers for their meeting will be drafted by Oliver Robbins, her EU adviser; • The government is set to "significantly increase the pace and intensity" of negotiations with a new "divide and rule" strategy which would see ministers sell their plans directly to national governments, by translating the white paper into every language in the EU; • May signals she wants to fight the next general election by appealing for MPs, peers and party members to help draw up 1000 new policy ideas in the biggest overhaul of the party's policymaking process in a decade. US President Donald Trump is supportive of Britain's proposed divorce with the European Union. Credit:AP

Sir Bernard Jenkin, Sir Bill Cash and Iain Duncan Smith - all senior figures in the Eurosceptic ERG of 60 Conservative MPs who have known Bolton for a number of years - attended the meeting with him last week. Sir Bill said Bolton "gave a positive view of what he believed the President thought about Brexit". He said: "In advance of the President's visit there were some positive things said about potential trade deals." Loading Separately it has been reported that Trump is evaluating the costs of transferring or withdrawing troops from Germany, where the United States has its biggest contingent outside the country. Such a move would make the EU even more reliant on the UK's Nato contribution.

May wants to increase the pressure on Brussels to make progress on the Brexit talks by sending ministers to meet EU country leaders separately to explain the benefits of a UK deal. This "divide and rule" strategy would see ministers tailor messages for specific countries. One senior government source said this would take advantage of a "pragmatism" among member states, adding: "There are many in the Commission who would say 'look there are 2000 jobs lost in member states, that is a price worth paying for the UK being taught a lesson'." Loading At Friday's meeting in Chequers May will settle the row over whether Britain adopts a customs partnership with Brussels - which involves collecting tariffs on behalf of the EU - or the maximum facilitation option - which relies on new technology to avoid a hard border - by offering a single "take or leave it" option.