US President Donald Trump might visit Britain in May 2019 after the country's departure in March from the European Union, the US ambassador to Britain, Woody Johnson, said on Monday.Asked whether a state visit promised by Prime Minister Theresa May last year could be rescheduled to coincide with a commemoration of the end of World War Two in May, Johnson told BBC radio: "Between you and me, I think that would be a good time."Trump visited Britain in July and although it was not a formal state visit after wide public protests, he met Queen Elizabeth.Brexit marks a watershed in Britain's diplomatic relations with the world as it tries to reshape ties to Europe and bolster its long-standing "special relationship" with the United States under Trump's unpredictable presidency.Asked if Trump would like to come again for a state visit, Johnson said: "I would think the President would be in favor of it and looking forward to it because that was mentioned when he was over here, so if we can do that it would be, I think, a big positive."He said a deadlock in Britain's parliament, which means that it is unclear what shape Brexit will take, meant a solution was necessary. "The country is in need of leadership."Johnson reiterated Trump's view that the United States was looking forward to a "quick, very massive bilateral trade deal" after Brexit, but that did not "look possible" under the current terms on which Prime Minister Theresa May has agreed a draft deal to leave the EU.Trump said in November that May's deal sounded like it would be good for the EU and cast doubt on how that would affect US-UK trading arrangements.