The Telegraph has talked to more than a dozen ministers and senior aides both sides of the Atlantic about what is planned for the historic talks and the new US-UK relationship.

Mr Trump’s team was said to be considering a “passporting deal” which would allow British and American firms to set up and trade in each other’s countries with minimum regulatory hurdles.

At present, British banks have a passporting deal with European Union – which mean British banks can carry out financial services anywhere in the 28 member states under one set of regulations.

The EU has threatened to strip Britain of these rights when it leaves, and some experts fear this could see billions of pounds of finance lost to rival cities such as Paris or Frankfurt.

Any UK-US deal on passporting could form part of a new trade deal which some have said could be agreed in just 90 days once Britain has left the EU.

One source close to Mr Trump said any passporting deal “would form part of the discussions, it will be on the agenda” at the first meeting between Mrs May and Mr Trump. The source added that “promoting Anglo-American capitalism is in both their interests”.