LONDON – A couple was arrested Sunday afternoon by police after stripping naked and having sex on the splendiferous lawn that surrounds Windsor Castle, the home of Queen Elizabeth II, who was home at the time.

Japanese tourists filmed the couple, who only stopped when police officers arrived on the scene, witnesses said.

“One window from the guardroom opened up and when a soldier saw what was going on he told his mates — and lots of windows opened up,” witness Mark Robinson told The Sun newspaper.

“The couple did not care who was looking and just kept going as if they were in their own bedroom.”

So what was the Royal treatment doled out to the impetuous pair? Thames Valley Police said the man and woman were cautioned for outraging public decency.

Photo: NOT the couple in question.