Tyler Dooley, 25, and several other members of Meghan’s extended family had flown to the UK from the US ahead of her wedding to Prince Harry, despite not being invited to the actual ceremony.
According to The Sun, Mr Dooley had been out celebrating the big day at Bacchus nightclub in Kingston, late on Saturday, when he confessed to bouncers he was carrying a four-inch blade.
He handed it over but then, when he was told that police had been called and he could be arrested, fled from the area.
A source said: “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.”
Dooley had been referring to recent comments made by the US President in which he described the streets of the capital as being “like a war zone” due to a recent surge in knife crime.
Revellers at the bar said Dooley later returned to try and explain himself to staff.
Police attended but did not make any arrests. “Police were called at 12.05am on Sunday May 20 to a club in Union Street, Kingston-upon-Thames, where a knife had been seized by security staff,” a Met statement said.
“The suspect had left the scene prior to police being called. Officers attended the club at around 1.55am and recovered the knife. There has been no arrest.”
Dooley, a legal US cannabis farmer, had been out celebrating the wedding with his girlfriend, older brother TJ, 26, and mum Tracey.
They were not invited to the event on Saturday, where the only family member of the newly-appointed Duchess of Sussex in attendance was her mother Doria Ragland.