Downfall explores, for the first time, how the Sweeney (the Flying Squad),

The Elite Serious Organised Crime Unit and the Obscene Publications Squad (the Dirty Squad) descended to unprecedented levels of corruption in the 1960s and 1970s, leading the infamous gangster Charlie Richardson to say that 'the most lucrative, powerful and extensive protection racket ever to exist was administered by the Metropolitan Police'.

Sir Robert Mark, who became commissioner of the Metropolitan Police and cleaned it up, said that it was 'the most routinely corrupt organisation in London'. During his time as commissioner, 50 officers were prosecuted, while 478 took early retirement.

Using Metropolitan Police files obtained under Freedom of Information, which have not been accessed since the 1970s, author Neil Root can finally tell the story of how both the Flying Squad and Obscene Publications Squad of the Metropolitan Police became systemically corrupt in the post-war years, and how they reached a nadir in the mid-1970s. It also shows how this culture of corruption has been a blueprint for Met Police corruption today, and how the enormous near-autonomous power wielded by elite squads allowed the corruption to fester and grow.