The drummers were promoting a LGBT festival called "As One in the Park" due to take part in East London. During the intermission, they reported that she came out of the stage door in full costume and "clearly angered, she shrieked, 'Quiet! I'm trying to do a play in here! People have paid a lot of money for tickets.'"
One of Mirren's co-stars, Rufus Wright, who plays Prime Minister David Cameron in the production, also reported that he intervened, tweeting: "Just fulfilled a lifelong ambition by bellowing at 25 drummers to shut the f*** up. West End theatres got thin walls. You should have seen Helen. She came out in full Queen costume and shouted at the drummers too. Honestly. It was breathtaking."
In a report in the Daily Telegraph, Mirren is reported to have admitted to swearing, saying, "I’m afraid there were a few 'thespian' words used. They got a very stern royal ticking off but I have to say they were very sweet and they stopped immediately. I would love to track them down and invite them to see the play. I felt rotten but on the other hand they were destroying our performance so something had to be done…Paul Ritter and I could hardly hear each other speak and the audience couldn’t hear us at all."