A man armed with a pitchfork got onto the grounds of Prince Charles' country estate.
A spokesman for the prince says the case is a matter for police.
The Daily Mail newspaper says the heir to the British throne and his wife, Camilla, were asleep at the time of Tuesday's break-in.
A police spokeswoman says a 55-year-old man from Bristol was arrested for trespassing and released on bail. She says the man was detained on the grounds of Highgrove and did not gain access to any buildings.
Charles' Highgrove estate is located 75 miles west of London.