He blazed through the 90s, an explosive mix of hellraising laddishness and sheer comic talent. As the 68-year-old resurfaces in Rehab, a musical about a drug-addicted pop star, he hits the Groucho to relive his triumphs and ponder his regrets Keith Allen wants to meet me at the Groucho. Well, of course he does. "I haven't been here in 10 years!" he protests as we find a corner table. That's all very well, but no one …
