If the Reform UK leader is serious in his offer to be a bridge between Keir Starmer’s government and president-elect Donald Trump, the prime minister should hold him to it, says John Rentoul

I assume that speculation about Nigel Farage becoming Britain’s ambassador to the United States is based on little more than putting two and two together: that Farage is a friend of Donald Trump’s and that Keir Starmer will need help in managing his relationship with the next president.

In fact, the Clacton MP and leader of Reform UK ruled himself out of consideration two weeks ago, saying: “Clearly, I’ve decided to get back into elected politics, so I’m off the table.”

He could of course rule himself back in again. Two days ago, he wrote an article for the Daily Telegraph offering his services in an informal role: “If I can be helpful in any way when it comes to bridging the divide that exists between Starmer’s government and Trump, I will be glad to assist.”

The prime minister should take him up on his offer – not least because it might help him bridge the divide between the government and Reform’s voters. Farage may have been pompous, but he was right, when he wrote: “I might not agree with almost anything that Starmer and his cabinet stand for, but I do believe in something called the national interest.” Labour should hold him to that.

But Starmer is not going to make him our ambassador to Washington, and nor should he. I understand that the prime minister will decide whom to appoint in the next few days, and that the leading candidates are Peter Mandelson, David Miliband and Cathy Ashton.

None of these is an obvious “Trump whisperer” in the way that Farage is, but each is well qualified to manage the relationship between the two countries. That relationship is mostly an institutional one, between the permanent bureaucracies on either side, and it involves navigating the complexities of international trade, which is in the end mostly what Trump’s rhetoric boils down to.

Lord Mandelson, who is currently running to be chancellor of Oxford University, would have to pull out of that contest – but he has priceless experience in trade negotiations as a former European commissioner. Lady Ashton, who succeeded Mandelson as a British European commissioner and who was also a Labour minister, is supremely well qualified. While David Miliband, who has lived in the US for 11 years, is almost over-qualified for the job as a former foreign secretary.

Any of those would be a strikingly “New Labour” appointment – just as was the appointment today of Jonathan Powell, Tony Blair’s former chief of staff, as national security adviser. What is truly Blairite about them, though, is that they suggest that Starmer values ability and experience over ideology.

I understand that speculation in recent days that Karen Pierce, the current ambassador to Washington, would have her term extended by a year is misplaced, and that she will leave immediately after Trump is inaugurated on 20 January.

Whether or not the prime minister actually decides on her replacement in the next few days may be subject to revision. After all, it took Starmer three months to decide on Powell as national security adviser, but the important thing in that case is that he made the right decision in the end. Powell, who more than anyone else helped Blair put together the deal that brought peace to Northern Ireland, has a deep understanding of these issues.

Whenever Starmer chooses our new person in Washington, the first thing the ambassador-elect should do is pick up the phone to Farage. If it is Miliband or Mandelson, they could remind Farage of what he said the other day: “If it was the choice of the two, I’d choose Mandelson, but frankly I’d choose neither.”

But then they should take up his offer of help. Partly because they should follow Mandelson’s mantra: “Kill your enemies with cream.” But partly because he might actually be of some help.

As Farage said in his Telegraph article: “Perhaps the biggest worry that Sir Keir Starmer faces in policy terms is that Trump has announced a big tariff regime.” I suspect that the threat of tariffs on British exports to the US is mostly bluster, but it is not a risk that should be taken lightly. Whoever is appointed as our ambassador should recruit Farage to help to persuade Trump that such tariffs would be a bad idea.

That would be in the national interest.