It’s been 16 years since New York City Ballet appeared in London, and its too-brief visit to Sadler’s Wells offered a welcome chance to encounter a previously unseen range of repertory and personnel. Perhaps the company can never be what it was when I first saw it as a youngster – its founder George Balanchine still in charge, the likes of Suzanne Farrell and Edward Villella in their prime – but one cannot live off misty memories and what has emerged now certainly has living, evolving force.