David Belmar, 44, tried to enter Buckingham Palace on Monday but was caught, arrested, and charged.
Belmar tried to enter through the palace’s north gate, police told Sky News.
Queen Elizabeth II wasn’t in the building at the time.
Belmar was searched and police found a knife on him.They arrested him on suspicion of trespassing on a protected site and possession of an offensive weapon.
Police arrested Belmar “immediately,” said police.
That was not the case in September’s embarrassing breach, when an intruder was discovered prowling around the palace after scaling a fence, and an alleged accomplice was also arrested. That was judged one of the most serious incidents since Michael Fagan managed to sneak into the queen’s private chambers in 1982.
The Associated Press contributed to this report.