In an ironic twist, despite playing the leader of the hooligan firm, the Inter City Firm who are associated with West Ham United and therefore dislike Millwall, Gary Oldman actually supports Millwall (the hooligan firm in the film are called The Buccaneers, based on the real life Bushwackers firm).
"Oboe" (Andrew Wilde) the leader of the Birmingham hooligans has a North of England accent rather than a 'Brummie'/West Midlands one.