Nigel Farage will be made a “close but unofficial adviser” to Donald Trump after he enters the White House, a key ally of the new president has said.

Phil Bryant, the Governor of Mississippi, made the comments at a party thrown for Mr Farage on the top floor of the five star Hay Adams hotel overlooking the White House on Thursday night.

The news will cause consternation in Downing Street which has repeatedly tried to downplay the significance of Mr Farage to Mr Trump, describing him as an "irrelevance".

Nigel Farage attends a pre-inguration Party credit: Steve Finn/Splashnews

Shortly after he won the US Presidential election Mr Trump said Mr Farage would be a good British ambassador to Washington, forcing Number 10 to scotch the idea.

Mr Bryant described Mr Farage, the former UK Independence Party leader, as a “humble man who just believes in great Britain and trying to make sure it achieves that greatness”.

He added: “There is an opportunity for him to work directly with the president, we call it 'close but unofficial'.

“I think you will see that type of relationship between Nigel Farage and the president where he will turn to Nigel for advice about Great Britain.”

Mr Bryant continued: “I don’t want to speak for the president but I know that the president has a great deal of trust in Nigel Farage , and I think he is going to turn to him as an adviser and there would be none better.”

Mr Farage and Mr Trump met after the pair were brought together by Mr Bryant and his team after a meetng on the closing night of the Republican National Convention in Cleveland, Ohio, in July.

He also said that Britain is “going to be great again” after Brexit which Mr Bryant described as “Trump’s first victory”.

Mr Bryant – one of the few senior Republicans who campaigned for Mr Trump during the presidential election campaign - said: “I remind all our friends here – there is a reason they call it Great Britain. It is going to be great again.”

The party organised by US public affairs firm Goddard Gunster was attended by around 200 guests including Arron Banks, the millionaire supporter of Ukip, Conservative MP Nigel Evans, Lord Ashcroft, the former Conservative funder. Mr Trump did not attend.

Mr Farage told an audience of 200 at the party: “Brexit was great but Trump becoming the president of the USA is Brexit plus, plus, plus.”

He added: “I have spent most of my life in politics as the patron saint of lost causes, having to spend several hours every day drowning my sorrows with English pints of beer because that’s all I ever did.

“I really believe this for most of my life what happens in America in terms of social trends or developments we follow four or five years later. America is the leader.

“Now I would like to think that in our own little way was the beginning of what going to be a global revolution and Trump’s victory is part of that.”

He added: “2016 would be looked at as a year of great pivot, a year of great change, a year when nation state democracy reasserted itself, a year when proper decent values reasserted themselves.

“And in the year 2017 much of this revolution will continue across much of what is left in Mr Juncker’s European Union.”

“A mixture of joy and disbelief – there is a still disbelief. The time now is to end that disbelief and say ‘we did it’!”

Likening Mr Trump to former Republican president Ronald Reagan, he said Mr Trump was the “only person I have met in my life who makes me feel like an introvert”.

He said: “I am proud to have played my part not just in Brexit but in helping this man become the 45th President of the United States of America.”