The UK must respect President Donald Trump’s “strong and clear mandate for change”, the new UK ambassador to the US has told the BBC on his first day in the role.

Lord Peter Mandelson said the UK would not necessarily agree with every detail of Trump’s agenda, but added: “We have to respect and understand what drives him, what his mandate is to do, and how his allies need to adjust sometimes.”

The 71-year-old, one of the best known figures in British politics, spoke to the BBC on Monday shortly after he presented his diplomatic credentials to the US State Department and became the ambassador to Washington.

During the interview, he said his past criticisms of Trump were “ill-judged and wrong” and was pressed on the differences between the UK and US on Middle East policy.

Asked how he would approach the position of US ambassador, Lord Mandelson said there was already a “strong relationship between our government and a very warm personal relationship between [Trump] and our prime minister”.

“Each of us wants to grow our economies,” he said. “I think that what we need to do is to build a technology and investment relationship between the US and the UK that’s fit for the 21st Century. That’s where I want to focus.”

Last week, Trump told the BBC that tariffs on EU goods could happen “pretty soon” – but suggested a deal could be “worked out” with the UK.

US allies are also waiting nervously for possible tariffs on steel and aluminium, which could upend markets around the world.

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Lord Mandelson, who served in several Labour governments and is the first political appointee to the US ambassador role in 50 years, said he was “concerned” about the possibility of tariffs on the UK.

But he added: “We actually have a very balanced trade relationship between Britain and the US. I don’t believe that his tariffs are actually directly targeted at us.”

“That shouldn’t make us complacent, and I’m not complacent. I’m going to focus, in a laser-like way, on the dialogue between us to make sure that we do not become collateral damage in the US,” he continued.

“But in the meantime, I don’t think we should be overreacting.”

The political veteran who helped mastermind Labour’s renewal in the 1980s and 1990s, and was twice forced to resign from Tony Blair’s government, has staged a political comeback with his arrival in Washington.

He is understood to already be planning how best to deploy Prime Minister Keir Starmer, with officials considering inviting the president on a second state visit to London.

Lord Mandelson told the BBC that Starmer and Trump share a “warm personal relationship”, which should make trade negotiations easier.

“I believe that given the relationship that we have, we can always make our views known, best by the way, directly, and privately, we have a strong relationship that enables us to influence the president and his policies, where necessary.”

There is a clear difference of opinion between Trump and Starmer over the future of the Gaza Strip, however. President Trump has said that under his plan for taking over and rebuilding Gaza, there would be no right to return for Palestinians who leave.

Starmer, meanwhile, has said they “must be allowed home”.

Lord Mandelson told the BBC “the president has aired some interesting ideas” on the future of Gaza, adding that the US and the UK need to work together to achieve peace and security in the Middle East.

“I don’t think that we have reached the end of the road on what happens in Gaza and policies that, not just the United States but its allies, pursue in co-operation with President Trump and his administration,” he said.

“The British goal is very clear,” he added. “We want to create a safe and secure Israel alongside a secure and prosperous Palestinian state. Now, how we get there remains to be seen.”