Peter Mandelson has downplayed suggestions that Nigel Farage will be the next Prime Minister, but says he takes the Reform UK leader "seriously."

The UK Ambassador to the US was speaking following Reform's success in the local elections, which saw the party winning 677 of around 1,600 seats contested.

Mandelson, a key architect of the New Labour administration under Tony Blair, drew a comparison between Reform and his former party following their landslide election victory in 1997.

Farage had previously said he would be willing to help Mandelson negotiate with the Trump administration, saying: "I know these people, and in terms of trade, in terms of defence and in terms of intelligence, the US is our most important relationship in the world – forget Brussels."

Farage had previously offered to help the ambassador

The ambassador told an event in Washington: "I remember after we were elected in 1997, within a year we were losing by-elections.

"Within a year, I heard people say, ‘Oh, they got this colossal great majority at the election and what’s Blair done with it? Why hasn’t the world changed? Why hasn’t the country changed in a year? You know, people are impatient."

Despite the fact he admitted that while he takes Farage "seriously" he said: "I’m not sure [the recent success] translates into people imagining that he’s going to be Prime Minister.

"When I was in government and I organised the election that we did in 1997, we didn’t have the same volatility of nationalism and populism that exists."

Tony Blair wiith then Secretary of State for Northern Ireland Secretary Peter Mandelson in 2000

Mandelson continued: "We didn’t have as fragmented a political system. We certainly didn’t have Nigel Farage.

"The reason why politics has changed is partly because of the global struggle, partly because of the social impact of rapid globalisation and the impact of that on people’s lives."

Eyebrows were raised when Mandelson was announced as the UK ambassador, given he had previously described Trump as a "bully" and "a danger to the world."

Speaking at the event in Washington run by the Financial Times, he said: "There is something about the president...he’s actually a rather gracious individual and he is funny, and he is obviously a people person so he responds to personalities."

President Donald Trump shakes hands with Britain's ambassador to the United States, Peter Mandelson

The United States and Britain announced a deal to lower tariffs on some goods last week, with US levies on cars and steel being cut and both sides gaining better access to agriculture markets.

Commerce Secretary in Washington Howard Lutnick said the 10 per cent basic tariff rate would remain in place.

President Trump said talks with Britain on his plan to impose tariffs on film imports would happen separately from the agreed deal.

He said: "James Bond has nothing to worry about."