Meghan Markle's nephew attempted to take a knife into a nightclub near Windsor Castle because he was worried by Donald Trump's saying London was "like a warzone".
Tyler Dooley, the 25-year-old son of the Duchess of Sussex's brother, Thomas Markle, was not invited to the wedding, but travelled to London with the intention of appearing as a pundit on television.
On Saturday night he went to the Bacchus nightclub in Kingston with his mother Tracy - Mr Markle's ex-wife - and his older brother TJ, 26.
As their party was searched entering the club, Mr Dooley, a cannabis farmer from Oregon, realised the four-inch blade would be discovered, and told bouncers on the door that he had a knife.
He told another partygoer, according to The Sun: “I just brought it because Donald Trump said London was like a war-zone. I had it for protection.”
The US president made the remarks on May 4, when he tried to defend America's gun laws by saying that, despite Britain's gun laws, knives made London a very dangerous city.
Mr Dooley left the scene after other clubbers told him he would be arrested, after security called the police.
The Met confirmed that they had received a call.
“The suspect had left the scene prior to police being called," a spokesman said.
"Officers attended the club at around 01:55hrs and recovered the knife. There has been no arrest.”
A source told the paper: “They were all obviously a bit tipsy from celebrating the wedding, but not in bad spirits. As Tyler came up to the bouncer, he said, ‘I have a knife on me.’ He pulled it out and handed it to the staff.
“All he was going on about was how he’d brought it from America because Donald Trump had said London wasn’t safe.
“They acted very calmly and dialled 999 and that’s when some local guys told him he’d get arrested. At that point he ran off.”
The Dooleys have declined to comment, and reportedly "hid inside a bin cupboard at the Hilton DoubleTree hotel" when The Sun asked them about the incident.