Kim Darroch, Britain's former ambassador to the US – who was forced to quit after leaks showed he described Donald Trump as inept and insecure – said warnings that the departing president's tenure could end disastrously were borne out.
In confidential diplomatic cables leaked in July 2019, Mr Darroch said that Mr Trump's presidency could "crash and burn" and "end in disgrace".
The comments angered Mr Trump, who said he would no longer co-operate with Mr Darroch.
Boris Johnson, at the time a Conservative leadership candidate and the front-runner to succeed Theresa May as British prime minister, was criticised for not giving Mr Darroch his full backing.
Mr Darroch told Sky News that given five people had died during the storming of the US Capitol this month, it would be "a little self-obsessed of me to see it all in terms of vindication".
“I made those judgments back in July 2017. They didn’t seem to me difficult or chancy judgments,” he said.
“If you watched the Trump campaign for the presidency and the chaos and disruption and ineptitude of the first six months, that seemed to me a pretty safe call and, I would say, so it has turned out."
Mr Johnson said on Wednesday he looks forward to working with Joe Biden on their "shared priorities", just hours before the latter's inauguration.
Mr Johnson said tackling climate change, recovering from the pandemic and transatlantic security are issues high on the agenda.
Meanwhile, WikiLeaks founder Julian Assange did not receive a presidential pardon from Mr Trump during his final hours in office. The departing president on Wednesday pardoned 73 people, including his former aide Steve Bannon and the rapper Lil Wayne.
The US Justice Department in 2019 asked Britain to extradite Mr Assange to face charges that he conspired to hack American government computers and violated espionage laws.
A judge ruled that Mr Assange, 49, should not be extradited to the United States, because his mental health problems meant he would be at risk of suicide.
