Warren has promoted and managed world champions and top ranked fighters including Naseem Hamed, Frank Bruno, Tyson Fury, Josh Warrington, Joe Calzaghe, Nigel Benn, Billy Joe Saunders, Steve Collins, Chris Eubank, Amir Khan and Ricky Hatton.
Warren agreed to become an unlicensed promoter, getting McLean a trainer who had worked with Chris Finnegan, and made the rematch at the Rainbow Theatre, Finsbury Park.
[3] Warren's first licensed show was held at the Bloomsbury Crest Hotel, in London in 1980,[2] promoting two unknown United States heavyweights.
However Warren was later given his first TV date with the BBC in a British light welterweight fight between London's champion Clinton McKenzie and Coventry contender Steve Early.
[3] Warren soon became a leading figure in British boxing, and since has managed some of Britain's best boxers of the last twenty five years, including 'Prince' Naseem Hamed, Nigel Benn, Joe Calzaghe, Ricky Hatton, Derek Chisora, Nicky Piper and Amir Khan.
[5] Warren guided Hamed to become Britain's youngest ever world champion when he beat Steve Robinson to win the WBO Featherweight title at the Cardiff Arms Park, Wales, in 1995; he oversaw the ascent of Ricky Hatton to the IBF Light Welterweight Championship of the World after beating Kostya Tszyu in 2005; and has been with former IBF and WBO/WBC/WBA/Ring Magazine Super Middleweight Champion Joe Calzaghe throughout the majority of his 46 fight unbeaten career.
[6] On 5 February 2016, gunmen stormed the Regency Hotel in Whitehall, Dublin during a weigh-in for the WBO European lightweight title bout between Jamie Kavanagh and Antonio João Bento.