Gwen Stefani is joined by George Clooney and Julia Roberts for Carpool Karaoke

James Corden was joined by the No Doubter to run through her catalogue of hits - before being joined by some pretty A-grade back up singers

James Corden will never let you be free of his Carpool Karaoke - and if he has to bring in two of the biggest Hollywood stars alive to keep you hooked, that's exactly what he'll do.

The latest installment saw the talk show host joined by No Doubter and ultra-Californian Gwen Stefani, rattling through her epic musical career; starting with the soulful likes of No Doubt's first big hit "Don't Speak", before revisiting her solo output "The Sweet Escape" (from the 2006 album of the same name).

The singer then professed her love for the emoji, before the pair launched into her 2015 track "Used to Love You", from her latest album This is What the Truth Feels Like and classic track "Rich Girl".

Realising he needed two more passengers to use the carpool lane, Corden then phones up the one guy he knows won't be busy: George Clooney, who in turn recruits frequent co-star Julia Roberts. Two people who clearly happen to be major fans of Stefani's "Hollaback Girl"; so much so, that Clooney is part of that minute section of the population who actually knows what a Hollaback Girl is.

Though he's pretty keen to get confirmation of his beliefs, Stefani's keeping tight-lipped about who the song's actually directed to. Truly, that sh*t is bananas.