The need to avoid protectionism is expected to be the major theme of Mr Brown’s speech on Wednesday to both houses of Congress, many of whose members want Mr Obama to defend US businesses by erecting barriers to foreign imports.

Mr Brown is only the fifth UK Prime Minister to be granted the honour of an address to Congress, and he will be watched by his wife, Sarah, who will also meet the President’s wife, Michelle, Obama in a “spouse’s summit”.

However, it is not thought the two wives will join their husbands for their working lunch at the White House today.

Mr Brown will present Mr Obama with the gift of an original commissioning document from the 19th-century exploration vessel HMS Resolute, from whose timbers the Oval Office desk – a present from Queen Victoria – was constructed.

The President will also receive a desk ornament made from timber from Resolute’s sister-ship, HMS Gannet, and a first edition of Martin Gilbert’s seven-volume biography of Winston Churchill.

Soon after becoming President, Mr Obama ordered the removal of a bust of Churchill – presented to his predecessor George Bush by Tony Blair – from the Oval Office, replacing it with a bust of his hero, Abraham Lincoln. There was speculation that the decision reflected Mr Obama’s unease with a reminder of the man who ordered the crackdown on Mau-Mau rebels in 1950s Kenya, during which his grandfather was detained and reportedly tortured, though the White House insisted it was no more than spring-cleaning after the change of administration.