Theresa May has sealed a major diplomatic coup by becoming the first world leader to secure a meeting with President Donald Trump at the White House.

It is understood the prime minister will travel to Washington in the coming week for an audience with the new US president at which plans for a post-Brexit UK-US trade deal will be high on the agenda.

Trump said on Saturday – his first day in office after Friday’s inauguration – that she would visit him “very shortly”. Downing Street declined to confirm the meeting last night but sources in Whitehall and the US indicated it would go ahead, with a slot on Friday pencilled in as the most likely space in the presidential diary.

May and her team will see the occasion as a chance not only to show that the president is on side with her plans to develop new trade arrangements with Washington after Britain leaves the European Union, but also more broadly to re-emphasise that the special relationship between the two countries is alive and well in the broadest sense.

Beating other leaders to the White House after the Trump inauguration has been a key objective for May and her government since his victory over Hillary Clinton in November.

Both Tony Blair and Gordon Brown were able to boast being the first European leaders to meet new presidents during their times as prime minister. Blair won the race to meet President George W Bush in 2001 and Brown was the first to meet President Barack Obama in 2009.

The joy in Downing Street will be all the greater given their anguish over recent months at the attention lavished on former Ukip leader Nigel Farage by Trump and his team in the aftermath of last year’s US election.

Causing intense irritation inside No 10, Farage became the first UK politician to meet Trump following his election victory. Unsurprisingly he milked the occasion, sending a tweet with a picture of himself and Trump in front of gold doors in Trump Tower in New York, and commenting that it had been a “great honour” to meet the man whose victory stunned the world. May was only the 11th world leader called by Trump after his election triumph.

The invitation to May this week will be ample, if belated, compensation and be viewed as evidence of Trump’s genuine willingness to help Britain make a success of Brexit. It will also be seen in other European as an implicit snub to the EU which Trump has described as a mere “vehicle” for Germany.

In a recent interview with former Cabinet minister Michael Gove, Trump said he thought “Brexit is going to end up being a great thing”.

Discussions between the two leaders could prove tricker over issues defence, and particularly Nato, after Trump raised doubts about his commitment to the western alliance.

May, who unlike Trump is known for measuring her every word, has said she will hold very “frank” discussions with the president and has been openly critical of some of his more outspoken remarks, notably about women.