Fitness was the focus at the opening party the other night for the new Krizia boutique in London’s Bond Street. Marguerite Littman said she’s been keeping fit by swimming daily at the new Chelsea Harbour Club, a favorite of Princess Diana’s. Designer Bruce Oldfield, who plans to hold a show in New York in May, proudly said he gave up smoking four weeks ago — with the help of a hypnotherapist. And Aldo Pinto of Krizia was singing the virtues of golfing and sailing in Sardinia. Pinto faces a difficult choice this summer, though. His wife Mariuccia Mandelli is designing the costumes for the Noel Coward-Cole Porter musical review “Let’s Do It” at the Chichester Theater and the couple will come back to London for the premiere at the end of July. “The problem is I’m supposed to be in Sardinia playing golf. But I guess I’ll have to come,” Pinto said sadly. Meanwhile, Greta Scacchi was chatting away in Italian to Mandelli, presumably about the clothes Krizia is designing for the actress for the Cannes Film Festival.