Of all the qualities required to write a novel, confidence is one of the most vital. Philip Hensher has confidence in spades, not only in his reach but in his readers’ stamina. His self-assurance and brio invests The Emperor Waltz with quasi-Victorian breadth and length, and with stylish authority. I was seduced into complete trust and abandoned myself to it completely. I barely noticed the pins and needles.  We follow, in counterpoint, the disparate lives of two young gay men, an artist beginning his studies at the avant-garde Bauhaus art school in 1922 and an entrepreneur who inherits enough money to open London’s first gay bookshop in 1979. They are each encouraged by like-minded pioneers and each, mutatis mutandis, comes in the end to settle for wry compromise. With s