Silence for the queen, please.
Mirren is starring in "The Audience," a drama about the weekly meetings between the queen and Britain's prime ministers over her 60-year reign.
Mirren told the Daily Telegraph newspaper that she used less-than-royal language in the rant during the intermission of Saturday's performance.
"I'm afraid there were a few 'thespian' words used," Mirren was quoted as saying Monday. "They got a very stern royal ticking off but I have to say they were very sweet and they stopped immediately.
"I felt rotten, but on the other hand they were destroying our performance so something had to be done."
The drummers were marching through London's West End to promote "As One in the Park," a gay music festival being held later this month.
"Not much shocks you on the gay scene," parade organizer Mark McKenzie told the Telegraph. "But seeing Helen Mirren dressed as the queen cussing and swearing and making you stop your parade — that's a new one."
Festival spokesman Mark Williams said organizers "are terribly upset if we caused her any distress. If she'd like to let her hair down and attend the festival she'd be more than welcome."
Copyright 2013 The Associated Press.