Billy Preston: In 1969 George Harrison invited Billy Preston, who has died aged 59, to join the Beatles for the recording sessions that would become the Let It Be album and the accompanying documentary film.
During those tense sessions, it was Preston's beatific presence on keyboards that glued the band together; he also played on the Abbey Road sessions and at the London rooftop concert that turned out to be the Beatles' final performance.
Preston was a magnificent musician and that association with the Beatles can tend to downplay his talent. Yet it did make him, with his huge Afro and gap-toothed grin, something of a pop culture icon in the early 1970s and helped him achieve solo success.
Preston was born in Houston, Texas, shifting with his mother, Robbie Preston Williams, to Los Angeles, aged one. Williams was a pianist and choir director and Billy followed her into the gospel world on piano, aged three, then on organ, aged six.
His introduction to show business came when the 10-year-old Preston was cast as the young WC Handy in the film St Louis Blues (1958).
The early 1960s were spent with the Rev AA Allen as he performed barnstorming evangelical tent revivals and recording pioneering soul-gospel sides with Allen Preston, James Cleveland and Andre Crouch. Preston's introduction to playing secular music came about when Little Richard, the rock 'n' roller turned evangelist, hired him as a sideman for a 1962 tour of England and Germany.
Richard thought he had been booked to play gospel but when British audiences clamoured for the hits he obliged. While in Hamburg, Preston struck up a friendship with the then unknown Beatles. Also on the tour was Sam Cooke and, when the musicians returned to the US, Cooke had Preston play on his recordings and sign to his label.
In 1966 Preston cut The Wildest Organ In Town for Capitol, an album arranged by a young Sly Stone. Those early recordings, while never hits, have become highly rated by northern soul aficionados. In 1967, Preston met Ray Charles, who hired him to play on Let's Go Get Stoned.
Two years later, while in England with Charles, Preston reacquainted himself with the Beatles. Preston's organ break on the 1969 number one Get Back found him receiving a label credit - the only time the Beatles ever shared it - and being signed to Apple, their label.
He joined the Rolling Stones for several early 1970s sessions, touring with them in 1973 as both support act and sideman before falling out with them over money. Preston also developed a cocaine addiction.
In 1972 he signed with A&M Records and topped the US R&B charts with a funky clarinet instrumental, Outa-Space, which won him a Grammy. He then hit number one in the pop charts with the vocal Will It Go Round In Circles, scored another R&B number one with the instrumental Space Race and repeated his pop triumph with 1974's vocal Nothing From Nothing.
The album this was from, The Kids and Me, also contained a ballad co-written by Preston, You Are So Beautiful To Me, which Joe Cocker successfully covered.
Preston played sessions with Aretha Franklin, Barbra Streisand and Bob Dylan - and Miles Davis named an instrumental after him.
Preston signed to Motown in 1978 but enjoyed only minor success. He continued to record both pop and gospel and in 1989 toured with Ringo Starr's All Star Band.
The 1990s saw Preston hit rock bottom: in 1991 he was arrested on morals charges; in 1992 he was given a suspended sentence on drugs and assault charges; in 1998, he pleaded guilty to insurance fraud.
Released from jail and drug free, Preston appeared in the film Blues Brothers 2000 and performed at the 2002 Concert For George organised by Eric Clapton to mark a year's passing since the death of Harrison. Preston then recorded and toured with Clapton and joined Ray Charles on his final album, Genius Loves Company. He cut a tribute album, Billy Preston's Beatles Salute, in 2004 and was employed by producer Rick Rubin to play on both Neil Diamond's 2005 12 Songs album and the Red Hot Chilli Peppers' 2006 Stadium Arcadium.
Preston had damaged his kidney through drug abuse and, last November, after his body rejected a transplant, he slipped into a coma from which he never recovered.
William Everett Preston, musician: born September 9th, 1946; died June 6th, 2006