Nice to know that after 14 years of existence, the London Gay Symphony Orchestra is finally getting acceptance by the arts establishment. On May 2 they are to make their Festival Hall debut - albeit in a rather aslant way, to perform the European premiere of Sing for the Cure, a symphonic song cycle chronicling stories of breast cancer survivors, as part of the Various Voices festival. But it’s a start, even if a late one, and you can hear how good they really are six days earlier when they will be essaying Tchaikovsky, Wagner and Poulenc a few yards from the RFH at St John’s Church, Waterloo.