“Not as easy as it used to be,” groans Harrison Ford’s swashbuckling archaeologist after a punishing burst of derring-do in the opening scene of Indiana Jones and the Kingdom of the Crystal Skull. A wry acknowledgement of the time that’s passed since Indy’s last big-screen adventure, the words could just as easily come from the sexagenarian star himself or, indeed, from director Steven Spielberg or executive producer George Lucas.It’s been 19 years since we last saw Indy in the cinema, battling wartime Nazis in Indiana Jones and the Last Crusade, and in the meantime a stream of younger and fitter stars, including Matt Damon’s Jason Bourne and Daniel Craig’s James Bond, have set bruising new standards for muscular screen action.Ford, who turned 65 during filming, actually looks in pretty good nick in the movie, but neither his surprising vigour nor the presence of Shia LaBoeuf as the young greaser (modeled on Marlon Brando’s biker in The Wild One) who becomes Indy’s sidekick can prevent the franchise from showing its age.Of course, the Indiana Jones movies – Lucas and Spielberg’s nostalgic homage to the Saturday-morning adventure serials of their youth - always did have a wilfully old-fashioned feel to them. Set in 1957, Kingdom of the Crystal Skull’s story, which sees Indy trying to stop Cate Blanchett’s rapier-wielding Russian parapsychologist and her team of Soviet agents from seizing a legendary crystal skull with psychic powers and taking over the world, is a conscious throwback to the era’s sci-fi B movies.But the kind of action that was funny and exciting in Raiders of the Lost Ark now looks incredibly dated. When Indy dukes it out with a hulking Russian soldier, the old-school two-fisted slugfest rapidly becomes boring. Even more unforgivably, during the film’s interminable stretches of exposition, Ford’s Indy comes across as a dull pedant.Now and then the movie sparks into life. There’s a chilling sequence early in the film in which Indy stumbles into a suburban