Since he returned from breakdown-induced wilderness, with rapturously received performances of the Beach Boys's 1966 masterpiece, Pet Sounds, a mini-industry has sprung up around Brian Wilson. There have been endless tours, poorly received solo albums and now, with Wilson no longer writing songs, Brian Wilson Reimagines Gershwin, an album remodeling George Gershwin classics in the style of the Beach Boys.

Promoting it is ostensibly why Wilson is in … well, he's not entirely sure. "Are we in Thishead?" he asks, "My teleprinter says it's Newcastle." Somehow, the revelation that even Wilson's asides are scripted isn't a surprise. The troubled Beach Boys legend may no longer have the psychiatrist Eugene Landy controlling him, but here we discover that saxophonist Paul Mertens "helped" Wilson reimagine Gershwin's songs. They're not ghastly, but not great. They Can't Take That Away from Me is awkwardly remodeled via California Girls, and Wilson's bark through It Ain't Necessarily So makes it sound as if Moses was found "in a strim". After just 40 minutes, nobody – least of all the artist - seems heartbroken that this segment of the show is over.

By contrast, an hour and a half is given over to Wilson's greatest hits. With band members taking lead vocals and embarrassing scripted banter, much of the time it's like watching a giant tribute band who just happen to have Wilson on stage with them. And yet, as Wilson dips into a fantasy set-list, he reaches towards the keyboard, smiles, and increasingly seems involved. Where his late brother Carl once sang lead on the hallowed God Only Knows, Wilson bravely gives the song a heartbreakingly fragility. Spines visibly tingle as Heroes and Villains, Help Me Rhonda and the rest sound exactly how they should. By the time Wilson delivers a glorious Good Vibrations, "Thishead" is on its feet, honouring the fact that the 69-year-old man who wrote some of the 20th century's greatest songs is still able to sing them.