LONDON, July 13 (Xinhua) -- A controversial balloon depicting U.S. President Donald Trump as an angry orange baby, dressed in a diaper, was flying in Parliament Square next to the Houses of Parliament on Friday as thousands prepared to march in protest at his visit to Britain.

A large crowd of anti-Trump protesters mingled with sightseers and tourists as the large inflatable balloon, tethered to secure ropes, made its ascent.

The president is unlikely to see the balloon as he made his journey by helicopter from the U.S. ambassador's residence in Regent's Park to watch a military display at Sandhurst, the famous academy for the training of military officers.

Later Trump was heading to Theresa May's country retreat at Chequers for bilateral talks.

May and Trump will later give a press conference which might give the first responses by the two leaders to an interview Trump gave to the Sun newspaper saying the latest British proposals for a trade deal with the European Union would rule out a future trading deal between the United States and Britain.

London mayor Sadiq Khan's giving permission to fly the balloon has evoked as much controversy as the president himself.

One British family, now living in Nevada, described the Trump balloon as humorous, while Conservative MP Nicholas Soames described it as utterly pathetic pointless and graceless.

After his meeting with May, Trump will complete his two-day business trip with an audience with Queen Elizabeth at Windsor Castle.

Tens of thousands of people were gathering in London for a protest march, with anti-Trump protest marches also scheduled in other major British cities.

After his meeting with the British monarch, Trump will journey to Scotland to spend the weekend at his golf resort in Ayrshire. Trump's mother was born in Scotland.?