The Queen and Prince Philip were at Sandringham at the time of the incident.
A Buckingham Palace spokeswoman said they would not comment as it was a police matter.
More top news
A Royal Marine from Northern Ireland who built explosives for an Irish republican paramilitary group had 43 hides, a court has heard.
A gay man has spoken of pain he suffered as a young boy when doctors gave him chemicals and electric shocks in attempt to 'cure' him.
Showers in the north tonight, elsewhere mostly dry.