A man was arrested after climbing the gates of Buckingham Palace, where Queen Elizabeth II is currently in residence, officials said Thursday.
The 22-year-old police officer, who was unarmed, was arrested around 2:00 am (01:00 GMT) on Wednesday and the incident is not being treated as terrorism-related, police said.
The Sun reported that the intruder was loose on the palace grounds for about four minutes before the arrest.
A spokeswoman for the palace confirmed that Queen Elizabeth, who met weekly with Prime Minister Theresa May on Wednesday, was staying at the palace.
There have been several security breaches in and around the palace in recent years.
More famous, in 1982, Michael Fagan entered the private apartments of Queen Elizabeth while in bed.
Last year, a homeless man climbed the walls and lay down to spend the night on the grounds before being stopped.