"Never trust a hippie," the Sex Pistols used to say. More precisely, perhaps, never trust an old hippie to put on a show. Edinburgh was promised an open-air extravaganza by the original West Coast acid guru Ken Kesey and his Magic Bus, with full complement of Merry Pranksters. Instead, Kesey and his old travelling companion Ken Babbs delivered an extended opener for Spiritualised, whose set with composer Steve Martland and a seven-strong choir convincingly recreated the astral ambience of the Roundhouse circa 1973.

Unable to deliver their full Arthurian pageant, Kesey and Babbs could only describe it - "and then there's Mordred, the bad head". Their acolytes in the front row seemed to be third-generation Pranksters, wearing Grandma's tie-dyes and practising grins learned from videos of the Monterey Festival. The only Prankster to take the stage was the Blue Fool, an American in a jester's sap, who sang Yeats in the style of Jim Morrison; for all I know, he was Oliver Stone moonlighting.

Kesey and Babbs announced, "We are the psychedelic revolutionary warriors of today," but they look more like a couple of benign old tugboat skippers. Kesey is a dead ringer for Norman Mailer, though nowhere near as pugnacious. The majestically bellied Babbs was mainly there to mutter, "That's right, man," every now and then.

As a raconteur, Kesey isn't quite in the Ancient Mariner league. Topics included Albania, OJ Simpson, Star Trek, Timothy Leary and the internet: "I mean, the internet is this thing." Allen Ginsberg's dying moments were recalled; apparently his last words were "Toodle-oo".

The two Kens admit to being a bit behind on their drug lore these days. They still recommend grass but warn against "the five evil ones" (coffee, alcohol, tobacco, sugar and pork). And they still preach universal love: we have to open the door, apparently, to both Mother Teresa and Hitler. Maybe they haven't quite thought this one through.

The sages ended by quoting the benediction of Bill and Ted: "Be excellent to each other and party on". It's come to a pretty pass when a 60s counter-culture icon ends up quoting the wisdom of Keanu Reeves. Kesey, of course, doesn't really need to be illuminating, he just needs to turn up. He is, after all, a legendary living relic. But then so is the coelacanth, and it probably tells better stories.