As with that other production about transsexuals currently in the West End, Priscilla is based on an original movie and features a gay hero with a heterosexual past that produced a son. But unlike La Cage aux Folles, this Australian road-show starring Jason Donovan as one of three “gender illusionists” is not set to an original score but to juke-box hits. There is a limit to the entertainment value of men in frocks singing covers less well than the originals. Thirty minutes tops? This is nearly three hours.