"Carnival of Light", originally known as "Untitled", is an unreleased avant-garde recording by the English rock band the Beatles. It was commissioned for the Million Volt Light and Sound Rave, an event held at the Roundhouse in London on 28 January and 4 February 1967. Recorded during a session for the song "Penny Lane", "Carnival of Light" is nearly 14 minutes long and contains distorted, echo-laden sounds of percussion, keyboards, guitar and vocals. Its creation was initiated by Paul McCartney's interest in the London avant-garde scene and through his connection with the design firm Binder, Edwards & Vaughan (often called BEV, and headed by the partners Doug Binder, Dudley Edwards and David Vaughan).
Since the event, "Carnival of Light" has rarely been heard, and does not circulate on bootlegs. For McCartney, the piece came to hold significance in his efforts to be recognised as the first Beatle to fully engage with the avant-garde, over a year before John Lennon recorded "Revolution 9". In 1996, McCartney tried to release the track on the Beatles' Anthology 2 compilation, but its inclusion was vetoed by his former bandmates. McCartney confirmed that he still had the tape in 2008. As of 201<!--- Do not change unless you have a more recent comment from McCartney---->6, he was still considering releasing it.
Background
With their August 1966 album Revolver, the Beatles broke new ground in pop by departing from the genre's conventional notions of compositional form, instrumentation and engineering; in musicologist Walter Everett's description, it was also "an innovative example of electronic music". Around December, Vaughan painted a psychedelic design on a piano owned by Paul McCartney. When delivering the piano to McCartney's home in St John's Wood, he asked McCartney to contribute a musical piece for The Million Volt Light and Sound Rave. To Vaughan's surprise, McCartney agreed. This is the story offered in Barry Miles' 1997 biography Paul McCartney: Many Years from Now. Alternatively, McCartney later told music journalist Mark Ellen that it was Miles who asked him to contribute to the event, while author Howard Sounes said that Dudley Edwards of BEV asked McCartney for a musical contribution from the Beatles and received a tape of "Carnival of Light" soon afterwards.
The Million Volt Light and Sound Rave (sometimes referred to as the "Carnival of Light Rave") was an art festival organised by BEV as a showcase for electronic music and light shows. It was held at the Roundhouse Theatre in Chalk Farm, north London. Posters for the event promised "music composed by Paul McCartney and Unit Delta Plus". The latter was an electronic music group whose members included composers Delia Derbyshire and Brian Hodgson from the BBC Radiophonic Workshop and synthesizer pioneer Peter Zinovieff. In preparation for the event, Dudley Edwards took McCartney to meet Zinovieff at the latter's house in Putney in south-west London. There, Zinovieff played them an experimental composition "at such intense decibel frequencies", according to Edwards, "that many parts of my anatomy (including internal organs) began to perform an involuntary dance. I can only describe it as 'ecstatic twitching'."