The Guardian reported that three activists were planning a mock execution of Prince Andrew, younger brother of Prince Charles, with a guillotine to mark the royal wedding.
Prince William weds Kate Middleton at Westminster Abbey Friday.
Charles Knight and two others were arrested, said activist Mike Raddie who was with them.
The trio was preparing to drive their theatrical props, including a home-made guillotine and effigies, into central London when the police arrived.
"Chris was arrested first. He lay down on the pavement opposite his house to make the arrest difficult," Raddie was quoted as saying.
Raddie said the police also seized a van that contained their props, including a wooden guillotine.
He said: "It's a working guillotine but it doesn't have a blade - just wood painted silver."
The group had advertised it on its website and the event was called a "right royal orgy" with "rumpy pumpy and guillotines".
Published 29 April 2011, 08:22 IST