Bill Bratton, the man predictably dubbed "supercop" by the media, uses an interview in today's Guardian to stake his claim to the top job in British policing - commissioner of the Metropolitan police. Bratton, who served as the chief of police in Los Angeles and New York, is prepared to take British citizenship in order to win the post. But he tells the paper that Theresa May has been "adamant" in banning foreign nationals from applying.

Significantly, however, Bratton is known to be David Cameron's choice to run Scotland Yard, turning this into a trial of strength for the Prime Minister. The Spectator's James Forsyth, who is close to Cameron, writes that whether or not he forces May to back down, is an early test of whether he is prepared to move from being "a chairman of the board-style figure to being a chief executive".

Unsurprisingly, Cameron's decision to name Bratton as an adviser on gangs and crime has antagonised the police, who are wary of any further challenge to their authority and view Bratton as a dangerous maverick. Sir Hugh Orde, the president of the Association of Chief Police Officers, who is himself in the running for the Met post, commented at the weekend: "I am not sure I want to learn about gangs from an area of America that has 400 of them. It seems to me, if you've got 400 gangs, then you're not being very effective." He added that talk of importing foreign police chiefs was "simply stupid".

But Bratton makes an impressive pitch. With an eye to liberal opinion, he describes himself as a "progressive" who hired "more people from ethnic minorities, women, gay people and transvestite people" in order to make the police forces he ran more representative of the communities they serve. He derides his critics as "parachoial" and says he has always been an "outsider". The interview also makes it clear why Cameron is so attracted to Bratton. He tells the paper: "I've been an outsider in every department I've worked in. Bureaucrats change processes, leaders change culture. I think of myself as a transformational leader who changes cultures." This is the language of Cameron's "enemies of enterprise" speech, in which he launched a fierce attack on government bureaucracies. Indeed, it was Cameron who once described the police as "the last great unreformed public service". Whether or not he prevails on the Bratton question is an important test of his reforming instincts.

In the meantime, it will be worth watching to see what Ed Miliband has to say about all of this when he speaks at his alma mater, Haverstock School, today at 10:30am.