Celebrated boxing promoter and manager Mickey Duff passed away in his sleep early Saturday morning at the age of 84.

A vital figure in British boxing during its transition into the modern era, Duff worked with 16 world champions including Joe Calzaghe, Frank Bruno, John Conteh, Alan Minter and Lloyd Honeyghan.

The Polish born Londoner actually became a professional fighter in 1945 and punch swapped for three years in the paid ranks. He retired to become a salesman, but then formed a partnership with two promotional luminaries in Jack Solomons and Jarvis Astaire.

He never looked back.

Duff held the monopoly on the British boxing business in the seventies and eighties and his affiliation with the BBC led to a golden era of televised fights for the terrestrial network.

His career spanned several decades, but Duff decided to retire from the sport in 1999 following Billy Schwer’s failed attempt to dethrone WBC lightweight titlist, Stevie Johnson.

Barry Hearn, whose own promotional career crisscrossed with Duff’s paid his respects on Twitter, "Sorry to hear that Mickey Duff died today. RIP legendary promoter.”

Duff was inducted into the International Boxing Hall of fame in 1999.

Photo / Getty Images

Tom Gray is a member of the British Boxing Writers’ Association and has contributed to various publications.  Follow him on Twitter: @Tom_Gray_Boxing