Foreign Secretary Boris Johnson has been accused of being an "apologist" for US President Donald Trump by a former UK ambassador to the White House. Lord John Kerr, the chief diplomat for Britain in America under ex-Conservative Prime Minister John Major between 1995 and 1997, made the claims in an opinion piece for George Osborne's Evening Standard.

"Johnson has from the start been a Trump apologist: when EU foreign ministers met to compare notes on the Trump election victory he ostentatiously stayed away, dismissing their discussion in advance as a 'whingeram'," the crossbench peer wrote.

"When last heard from he was still maintaining there was no cause for alarm. Was he behind the unprecedentedly early state visit invitation? Is he Trump's poodle? If so, why?

"Could it be that he really believes, with [International Trade Secretary Liam] Fox, that provided we keep on sucking up a sweetheart transatlantic free trade deal may bail us out?

"Despite that 'America First' inaugural address that promised America 'protection against other countries making our products, stealing our companies, destroying our jobs'?"

Kerr, 75, also warned of a free trade agreement with the US under Trump. "A free trade deal with a president who denounces free trade is a mirage, and not standing up to him risks forfeiting respect all round," he said.

The comments come more than two months after the general election, which saw the Conservatives lose their majority of the MPs in the House of Commons. Before the 8 June vote, Theresa May was reportedly planning to replace Johnson with Brexit Secretary David Davis. Ben Gummer, an ally of May's, would then apparently head-up the Department for Exiting the EU under the plan.

But the vote saw Gummer lose his Ipswich seat, while May sought to unify her cabinet and MPs behind her. The prime minister's top aides – Fiona Hill and Nick Timothy – resigned from Number 10 as Johnson told his allies via text to get behind May.

Johnson, the lead campaigner for Vote Leave, has not been involved in the takes with the EU, with Davis taking on the EU's chief negotiator Michel Barnier.