Cameron Mackintosh gave us the mega-hit musical. As he turns 70, he tells Dominic Cavendish how he tore up the rulebook

Electronic ticket touts be warned: Sir Cameron Mackintosh is coming after you. The most successful theatre producer on the planet (who joined Britain’s list of billionaires two years ago) is determined that when the smash-hit Broadway musical Hamilton opens in the West End next autumn, it will not be bedevilled by the same phenomenon that has dogged its New York run, where tickets have been trading for hundreds of dollars.

For much of our conversation, Mackintosh, who owns eight West End theatres as well as being the impresario who gave the world those blockbusters Cats, The Phantom of the Opera, Les Misérables and Miss Saigon is affability itself, puppyish in his enthusiasm.

Yet I detect veins bulging in anger as he talks about the industrial scale of ticket-reselling online, and the rip-off merchants who have been running rampant. “It’s horrible and it has got to stop. In the old days, with Cats, you knew who the touts were. You’d pick them out of the queue and tell them to hop it. Now you’ve got these sophisticated computer programs hoovering up tickets – and you’ve also got members of the public tempted by those inflated prices trying to sell tickets themselves.