Woody Johnson said Britain has a “long history of overcoming adversity” and its move to leave the EU is no different.

He added he was “very optimistic” that Brexit will be a success because of the resolve of Britons.

Mr Johnson was answering questions while hosting a live question and answer session on the US’s London embassy’s YouTube channel.

When asked about a potential US-UK trade deal, the US Ambassador said: “We’re going to have trade negotiations after Brexit occurs.

“But, the planning for that is occurring right now and we’ve got various departments in the cabinet – Treasury, Commerce, trade and others – looking at the complex arrangements and treaties we have now and seeing how we carry those forward.

"When the time comes for us to begin those negotiations, we are totally prepared.”

Mr Johnson also revealed he has hosted numerous businesses looking to invest in the UK, despite doom-mongering reports that Brexit will kill inward investment in the country.

He said he had been to Wales with several American businesses, who all praised the country as a possible destination for investment.

Praising Welsh workers, Mr Johnson said: “There are two things that are really great, the people and the relationship with the Government.

“The people are the best workers you will ever find, they’re absolutely extraordinary, very loyal, very well educated and very smart.

“The relationship that these companies have with the Government is one of ‘let’s get on with business, let’s do something great for the people’.”

Mr Johnson has also said US President Donald Trump is “very excited” to visit London and Prime Minister Theresa May.

Mr Trump is due to make a “working visit” to London in February when he will formally open the new US embassy.