Man, 41, arrested in Buckingham Palace grounds after scaling wall
A 41-year-old man has been arrested in the grounds of Buckingham Palace after scaling a perimeter wall.
The suspect was in the grounds for seven minutes before being arrested on Wednesday night, police said.
Commander Adrian Usher, head of the Met's Royalty and Specialist Protection unit, said the security measures had "worked effectively" and "at no time was any individual at risk".
But Ken Wharfe, former protection officer to Diana, Princess of Wales, and William and Prince Harry, said the intruder was in the grounds for too long before being caught.
The Queen and the Duke of Edinburgh were inside at the time and have been informed of the security breach.
The man was held on suspicion of trespassing on a protected site shortly before 9pm.
He had climbed the outside perimeter wall to enter the grounds, leading the alarm to be raised. No weapons were found.
Mr Wharfe said: "It took seven minutes to find this guy, which is a hell of a long time. Ten seconds is a long time, a minute is a long time," he added.
"In 10 seconds you could run 50 yards, at the bottom end of the Palace that would take you into the front door of where the Queen lives, that's how accessible the Palace is from the perimeter wall at the bottom end."
He said the royal couple do not want increased security at the Palace and added: "The problem is the Queen will not want any further uniformed static responses outside in the grounds of her Palace - that's the end of it, it won't happen.
"There have been suggestions of increasing the height of the wall and so forth ... the royals won't put up with it.
"The Queen is quite adamant she doesn't want any additional people patrolling and she won't be convinced that that is the best course of action."
A Palace spokesman said: "We never comment on security, which is a matter for the police."
Former royal protection officer Dai Davies said that the arrest came "very quickly" after the alarm was raised, considering the size of the grounds.
He said: "He was caught by the police very quickly and the system seems to have worked, which is the main thing."
The Queen had earlier attended the State Opening of Parliament and will be at a garden party in the grounds of the Palace on Thursday afternoon.
A number of trespasses have taken place at the site in recent years, and the walls have been scaled several times.
Fathers' rights campaigners used a ladder to climb on the roof of the Queen's Gallery in November and spent almost eight hours on top.
In September 2013, a 37-year-old man got into the Palace building itself and was found in a room which was open to the public during that day.
The most high-profile breach came when Michael Fagan broke into the Queen's bedroom in 1982, spending around 10 minutes talking to her.
He too had climbed over the Palace walls before scaling a drainpipe.