David Benedict Is it a musical? Is it a roller derby? Is it a game-show? When the roller-skating phenomenon that is “Starlight Express” opened in London in 1984 it was all of those and more, as evidenced by its 18-year run. It lasted just 22 months on Broadway but in a uniquely created theater in Bochum, Germany, it has just entered its 37th year. Might North London’s much-vaunted new version in a specifically rebuilt theater emulate that success? Hope springs eternal, but given Luke Sheppard’s surprisingly strained and only intermittently exciting production, it’s going to need a massive marketing spend.