Tourists gather at the area in front of Buckingham Palace in central London, Monday, Oct. 14, 2013. British police arrested a man with a knife after he tried to dart through a gate at Buckingham Palace in London on Monday. The palace said Queen Elizabeth II was not in residence. Breaches of royal security are rare, but just a month ago police arrested two men over a suspected break-in at the palace. (AP Photo/Lefteris Pitarakis)

Photo by: Lefteris Pitarakis

Tourists gather at the area in front of Buckingham Palace in central London, Monday, Oct. 14, 2013. British police arrested a man with a knife after he tried to dart through a gate at Buckingham Palace in London on Monday. The palace said Queen Elizabeth II was not in residence. Breaches of royal security are rare, but just a month ago police arrested two men over a suspected break-in at the palace. (AP Photo/Lefteris Pitarakis)