On its most recent U.S. tour, the band played mostly large theaters as a sextet, with Bunton, usually the drummer, taking over Smith's bass and keyboard duties.

CNN: Soundcheck: TV on the Radio, a band to see and hear

Former Spice Girl Emma Bunton and TV presenter Kirsty Gallacher have also been lined up to cover Kelly's holiday absence and the final shows under the GMTV banner.

BBC: Fiona Phillips returning to GMTV sofa

But 'Posh' did take to the stage with Geri 'Ginger' Halliwell, Melanie 'Scary' Brown, Melanie 'Sporty' Chisholm and Emma 'Baby' Bunton at the end of the performance at London's Piccadilly Theatre.

BBC: Spice Girls musical leaves critics cold

Together, along with band mates Dave Sitek and Jaleel Bunton, they have created a unique sound that transcends genre classification and has elicited critical acclaim album after album -- most recently for their latest project, "Nine Types of Light, " which came out this year.

CNN: Soundcheck: TV on the Radio, a band to see and hear