Stephen Sackur speaks to perhaps the UK's most controversial police officer, a commander in London's Metropolitan Police and a convicted criminal. Ali Dizaei was born in Iran, studied law in London and became a high-flying spokesman for ethnic minority police officers in a London force dogged by accusations of racism. Ali Dizaei portrays himself as a victim; the courts decided he was a rogue cop. What does his rise and fall say about British policing?