The battle against cellphone use has another front along with Broadway — the West End.

When the actor Benedict Cumberbatch met with fans — and the glare of flash from their cameras — after a weekend performance of “Hamlet” at the Barbican theater in London, he had a message to send.

He told them that while he doesn’t use social media, he would be very happy if they did, just not during his performance.

“Can I ask you all a huge favor?” the actor said to fans gathered outside the stage door. “All of this, all these cameras, all these phones,” he said pleadingly, his voice trailing off. “What I really want to do is try to enlist you.”

“I can see cameras, I can see red lights in the auditorium. And it may not be any of you here that did that but it’s blindingly obvious, like that one there, that little red light,” he said, pointing into the crowd.