May will seek to put the diplomatic tensions behind her when she hosts Trump on Thursday for a black-tie dinner with business leaders at Blenheim Palace, the birthplace of World War II prime minister Winston Churchill.
"He's come out of the woodwork now and I've seen it the last few days; there's huge positivity for what we've done here".
Mr Trump arrived at London Stansted Airport at 2pm on Thursday for his four-day working visit.
Asked if his trip to Menie had been arranged to coincide with his father's presidential visit, Eric Trump said: "We had it planned a little bit before, and they happened to link up, so it's exciting".
Selectively quoting him after he urged people to remain calm, Trump blasted him on Twitter.
The Stop Trump Coalition accused the president of being "too scared to face protestors".More news: WhatsApp will now warn you against suspicious links
Johnson said he was "aware" of protests planned over the course of Trump's visit, including a giant "Trump baby" balloon that is expected to fly over Westminster during the trip.
Trump also had strong opinions on the UK's European Union referendum, describing Brexit as the United Kingdom people's exercising their will to self-determine. The people voted to break it up so I would imagine that's what they would do, but maybe they're taking a different route - I don't know if that is what they voted for'.
70,000 people are expected to attend an anti-Trump rally at Trafalgar Square tomorrow, with a march through Central London first.
Mr. Trump, however, suggested before leaving a North Atlantic Treaty Organisation summit in Brussels on Thursday to head for London, that Britons in general agree with his policies, in particular his tough stance on immigration.
"It's really kind of irrelevant to what we're trying to do and I don't think certainly it doesn't express the opinion of the British people I met", he said.
Trump will meet again with May for a visit to a defence site.More news: Face of Brexit Boris Johnson resigns, plunging May into crisis
One tweeter commented that Trump seemed to be "grabbing onto Melania's hand, to keep her from pulling it away, rather than just gently holding it!"
In anticipation of the unprecedented vitriol directed at a serving president, the U.S. embassy told Americans to keep a low profile and "exercise caution if unexpectedly in the vicinity of large gatherings that may become violent".
Trump's military entourage arrived at the Essex airport well before the U.S. president - who was delayed at a North Atlantic Treaty Organisation summit in Brussels after he made a surprise press conference about defence spending.
Mrs May will be looking to improve her often publicly strained relationship with the United States president as she pushes for a post-Brexit trade deal with America.
President Donald Trump will get the red-carpet treatment on his brief visit to Britain beginning today: military bands at a gala dinner, lunch with the prime minister at her country residence and tea with the queen at Windsor Castle before flying off to one of his golf clubs in Scotland.More news: Duke and Duchess of Sussex arrive in Ireland for tour