Britain can escape US trade tariffs that threaten to clobber British industry but Sir Keir Starmer must mend fences with Donald Trump without delay, according to Nigel Farage.

The Reform UK leader – who has a longstanding friendship with the incoming US President – said the Prime Minister faces a stark choice between delivering on the promise of Brexit and striking a transatlantic trade deal or signing-up to the diktats of the European Union.

Mr Farage said it is “essential” that Mr Trump is invited to the UK for a state visit in the year ahead and warned against choosing an ambassador to the US who the president is bound to vehemently dislike.

His intervention comes amid fears that Mr Trump will slap tariffs of between 10 and 20 per cent on all US imports. Britain exported goods worth £58.3billion to the States in the 12 months to August.

Summing up the choice for Sir Keir, Mr Farage told the Sunday Express: “Starmer is going to have the big dilemma over trade negotiations.

“Does he act in the British national interest for Brexit and negotiate a deal or does he let the EU dictate policy, because the Trump tariff regime is coming but we can avoid it.

“We need to make the most of these opportunities and clearly in terms of relationships there’s some very serious fence-mending that needs to take place.”

Mr Trump will be aware that foreign secretary David Lammy denounced Mr Trump as “a racist KKK and Nazi sympathiser” and as “a woman-hating, neo-Nazi-sympathising sociopath” before Labour took power.

Mr Farage says Britain must “roll out the red carpet” for the Republican leader.

He said a state visit in the summer would be a “very good thing” and was confident the president would get on well with King Charles.

“Obviously Trump had the most enormous respect for the late Queen but, equally, while he and Charles may not see eye to eye on some environmental issues he does like Charles very much,” he said. “He thinks he’s a very good man – there’s no question about that.”

Not only can Britain avoid tariffs, Mr Farage argues, a sector-by-sector trade deal with the US is there for the taking.

He said: “I think it’s on the table, it’s achievable and we should thank our lucky stars that we’ve got a strong US president who’s firmly pro-British.”

However, he is appalled by suggestions the next UK ambassador to the US could be former Labour foreign secretary David Miliband, ex-EU foreign policy chief Baroness Ashton or former EU trade commissioner Lord Mandelson.

Mr Farage said: “Are you having a laugh? Whilst I do have enormous respect for Mandelson’s intellect – he is a remarkable figure; I would never be personally insulting about Mandelson because he’s a very, very, very clever man – is somebody with the European Union tie appropriate for a president who hates the EU more than I do?”

According to former FT editor Lionel Barber, Mr Trump “feels that neither Tory nor Labour governments have made anything of Brexit”.

Sir Keir faces an internal row if he prioritises trade with the US over the EU. Labour’s election manifesto pledged that the Government will “improve the UK’s trade and investment relationship with the EU, by tearing down unnecessary barriers to trade”.

In the 12 months to August, UK goods exports to the EU were worth £179billion – 47.8 per cent of total exports.

The Prime Minister may also have to deal with anger at Britain’s decision to hand Mauritius sovereignty of the Chagos Islands – home to the US-UK Diego Garcia military base.

The base will remain in place for at least 99 years but there are concerns that China will exert influence on Mauritius.

Mr Farage said: “I think there’s going to be a row over the Chagos Islands and possibly a very big one. I spoke to a very senior Republican representative today and he said to me that he thought Diego Garcia was in some ways one of the most important islands in the world.”

The veteran Brexiteer has offered his services to the UK Government.

He said: “All I’ve said is that if I can help mend fences, build bridges – it isn’t just Trump I know; I know many of the senior team around him, I will know many of those that get appointed to cabinet positions – maybe I could be useful as an interlocutor if the Government choose to use me.”

Claiming that many people have the wrong impression about Mr Trump, he said: “They see Trump as a very aggressive, abrasive figure. Actually, he’s one of the funniest, most charming people I’ve ever met.”