But any good vibrations from that moment soon dissipated when Trump, the same day, announced plans to ban migrants from seven Muslim-majority countries - a decision that drew fierce global criticism and appeared to blindside May.
Trump then angered May and many Britons by retweeting unverified, anti-Islamic videos from Britain First, whose leaders have been convicted of hate crimes.
What has become increasingly clear is that neither of the Trumps are likely to see much of London during their visit.
President joins Lee Jae-yong at Samsung factory opening in India
Samsung's Noida plant, set up in 1996, has been manufacturing smartphones, refrigerators and flat-screen televisions. He said it is a matter of pride that India is home to the world's largest Samsung unit.
Trump is also expected to travel to Scotland, where he owns two golf courses.
On Friday, Trump will meet May and her newly appointed Foreign Secretary Jeremy Hunt at the prime minister's countryside retreat, Chequers.
Thousands are expected to protest across the capital, heavily led by Owen Jones" "Stop Trump' rally, which will go ahead on Friday July 13.
The US embassy's alert to American citizens was an unusual step, CNN reported.
It’s a European revolution at this World Cup
Belgium have reached the World Cup semi-finals for only the second time, losing out to eventual winners Argentina in 1986. Even though Lukaku did not have the desired impact for Chelsea, he credits Drogba for helping to shape him as a player.
Firebrand politician and Trump ally Nigel Farage labelled the move "the biggest insult to a sitting US President ever" but others have welcomed the playful rebuke.
Mr Smyth, who is originally from Ireland, said Trump fans had been given a bad rap, and there had been lots of support for the pub's temporary renaming. "The issue is 'Do they have freedom to protest, freedom to assemble and should they be allowed to do so?", he said.
The president's first official visit to the United Kingdom is expected to be overshadowed by mass demonstrations, with more than 50,000 people signed up to take part in protests in the capital.
May has had to defend Trump's visit in the face of fiery criticism from opposition lawmakers.
Why English soccer fans chant 'It's coming home'
With England taking aim at the grandest of prizes, '"It's coming home" has become the tagline to a remarkable campaign. Baddiel and Skinner created Three Lions with The Lightning Seeds in 1996.
It has vowed to gather near the U.S. ambassador's residence in London, where Trump and First Lady Melania Trump will stay Thursday night, and outside Blenheim Palace, wartime leader Winston Churchill's birthplace, which hosts the pair for dinner prior.