Born in Liverpool, law graduate Ellis (pictured middle, with Paul and Linda McCartney) worked in insurance for 10 years in New York and Chicago, before childhood friend Epstein contacted him in 1963, in need of help for the Beatles' first US trip.
Ellis left his job to help Epstein manage his quickly expanding business empire, and by 1964 – during the height of the Beatles' global super-stardom – he was director and chief administrator of Epstein's pop management company, NEMS Enterprises.
During his thirty five year career in the music business, Ellis became a key figure in running the business affairs of the Fab Four, as well as artists Gerry & The Pacemakers, Billy J. Kramer & the Dakotas, Cilla Black, and Elton John.
Following Epstein’s death, Ellis remained a director of Northern Songs – which owned John Lennon and Paul McCartney’s songs – and was asked by the band's music publisher, Dick James, to join him at his then burgeoning Dick James Music group of record and publishing companies.
It was there that Ellis found himself assisting in the management of another worldwide superstar; Elton John. He spent the next six years working with John's manager, John Reid, handling the business affairs of his management company.
In the nineties he was headhunted by former chief executive officer of PRS for Music, Michael Freeguard, who recruited Ellis to head up the PRS membership team.
In 2004, Ellis released his memoir, I Should Have Known Better: A Life In Pop Management, which detailed his experiences of the music business from the sixties to the mid-nineties, providing an insider's view of the careers of many of the most significant players.
He remained at PRS until his retirement, where he divided his time between London and France.
Ellis is survived by his partner of 45 years, Daniel Martin, to whom he dedicated his book.