He performed on many popular and enduring British and American rock music recordings from the 1960s to the 1990s, including on songs recorded by the Beatles, the Rolling Stones, the Who, the Kinks, the Steve Miller Band, Jefferson Airplane, Rod Stewart, George Harrison, John Lennon, Paul McCartney, Ringo Starr, The Hollies, Cat Stevens, Carly Simon, Harry Nilsson, Joe Walsh, Peter Frampton, Jerry Garcia, Jeff Beck, Joe Cocker, Art Garfunkel, Badfinger, Quicksilver Messenger Service and Donovan.

[6] Hopkins's studies were interrupted in 1960 when he left school at 16 to become the pianist with Screaming Lord Sutch's Savages until, two years later, he and fellow Savages Bernie Watson, Rick Brown (aka Ricky Fenson) and Carlo Little joined the renowned blues harmonica player Cyril Davies, who had just left Blues Incorporated, and became the Cyril Davies (R&B) All-Stars.

[7] Hopkins was forced to leave the All Stars in May 1963 for a series of operations that almost cost him his life and he was bed-ridden for 19 months in his late teenage years.

When working with the band during their critical and commercial zenith in the late 1960s and early 1970s, Hopkins tended to be employed on a wide range of songs, including ballads, up-tempo rockers and acoustic material; conversely, longtime de facto Stones keyboardist Ian Stewart only played on traditional major key blues rock numbers of his choice, while Billy Preston often featured on soul- and funk-influenced tunes.

Hopkins plays on 14 of the album's 18 tracks, giving him a greater presence than full time Rolling Stone Bill Wyman, who only contributed to nine of the songs.

[11] It was also incorporated into the title of Hopkins's instrumental song "Edward, the Mad Shirt Grinder", recorded with Quicksilver Messenger Service and released on Shady Grove in December 1969.

[14] Hopkins contemplated forming his own band with multi-instrumentalist Pete Sears and drummer Prairie Prince around this time but decided against it after the Stones tour.

His trademark licks and fills bounced effortlessly off the rest of the band and he received a rare songwriting co-credit for the riotous instrumental "The Ox".

He was also a key instrumentalist on the soundtrack for Ken Russell's 1975 film Tommy; Townshend had wanted Hopkins to play on the original 1969 album.

[citation needed] Hopkins also played on Space Jazz, the official soundtrack to infamous Scientology founder L. Ron Hubbard’s novel, Battlefield Earth in 1982.

After he accompanied three of the Beatles on Jackie Lomax's "Sour Milk Sea", he was invited to play an electric piano solo on the group's "Revolution", which he did in one take.

Intended as a vehicle for former Yardbirds guitarist Jeff Beck, the band also included vocalist Rod Stewart, bassist Ronnie Wood and drummer Micky Waller.

In August 1975, he joined the Jerry Garcia Band, envisaged as a major creative vehicle for the guitarist during the mid-seventies hiatus of the Grateful Dead.

His increasing use of alcohol precipitated several erratic live performances, resulting in him leaving the group by mutual agreement after a 31 December appearance.

One of his complaints throughout his career was that he did not receive royalties from any of his recording sessions, because of his status at the time as merely a "hired hand", as opposed to pop stars with agents.

[citation needed] His precarious health, a consequence of Crohn's disease and its complications, made touring very difficult, limiting him largely to studio work.

Only Quicksilver Messenger Service, through its manager Ron Polte, who went to great lengths to treat his musicians fairly, as well as with assent of the band's members, included Hopkins in an ownership stake.

[citation needed] In the early 1980s, Hopkins credited the Church of Scientology-affiliated Narconon rehabilitation program with curing his drug and alcohol addiction so he ultimately remained a Scientologist for the rest of his life.

[citation needed] In 1993, Hopkins, Joe Walsh, Terry Reid, Rick Rosas, and Phil Jones put together an informal group called The Flew.

[29][30] Hopkins died on 6 September 1994, at the age of 50, in Nashville, Tennessee, from complications resulting from intestinal surgery related to his lifelong battle with Crohn's disease.

Names that have pledged in the campaign include Mick Jagger, Keith Richards, Charlie Watts, Ronnie Wood, Bill Wyman, Yoko Ono Lennon, Roger Daltrey, Jimmy Page, Hossam Ramzy, Johnnie Walker and Kenney Jones.