Basic memory loss powers the adventures both of the eponymous spy in Jason Bourne and the blue tang fish in Finding Dory. He is played, as in the first three Bourne films, by Matt Damon, who was absent from the last one, 2012’s The Bourne Legacy. Jason Bourne, the film, has more puff than a nuclear cooling tower. It kicks off in a sweaty Balkan clearing where Bourne – like James Bond a loner and maverick, but no more likely to issue some sparky innuendo than flaunt a spare tyre – seems to be earning his corn as a bare-knuckle prizefighter. Around the time that Damon first played Bourne, the U.S. comedian Ellen DeGeneres was giving voice to a fish also blighted by amnesia.