LA’s legendary Chateau Marmont hotel is the embodiment of Hollywood excess, so it’s easy to understand why Jarvis Cocker, Sheffield’s all-seeing eye, would feel compelled to slink around its gothic walls to find the squalor beneath the glamour.

On Room 29, a concept album and elaborate, immersive stage show in collaboration with Canadian rapper-turned concert pianist Chilly Gonzales, Cocker inextricably links the rise of Hollywood with the hotel’s construction and its decadent inhabitants who did drugs off the piano, had wild sex and “ordered ice cream as main course”.

This being Cocker, his eye roams behind closed doors, where the veneer slips and Room 29 becomes a place of existential crisis: careers stall, spirits break and lives fall apart at the seams. “This whole place was built on a lie,” he breathily concludes over the title track’s sweet piano motif. “But what a lie.”

To demonstrate, the pair turns the Barbican into room 29 (where Cocker stayed for real five years ago). The audience are given room keys on entry; a bed and cabinet face Gonzales’ piano; Cocker enters suitcase in tow and starts unpacking his baggage before metaphorically sifting through other people’s.

What follows is a unique hybrid of pop gig, stage theatre and university lecture. The pair riff off each other in witty asides. In lengthy commentaries, Cocker uses footage both self-made and vintage to detail the tragic lives of Clara Clemens, Jean Harlow and Howard Hughes.

Theatrics range from droll (a string quartet is ordered from room service, a hotel porter pops in with drinks) to pointed: at one stage Cocker is transported into a television set, the reality of which fails to live up to his imagination.

Music Box Session #4: Bassette

Before a concluding cover of Leonard Cohen’s “Paper Thin Hotel” – with its proto-Jarvis lyric of sexual prying – the album is reprised in full.

The songs penned by Gonzales are mostly elegant things: “Tearjerker” has a plaintive piano line and some first class Cockerisms (“you’re a tearjerker/You don’t need a girlfriend/You need a social worker”), while “Ice Cream as Main Course” boasts the night’s standout melody.