Assistant Commissioner of Police of the Metropolis

There have usually been four officers in the rank; however, as of January 2025, there are six owing to the appointment of a new portfolio, Trust and Legitimacy, and the continuing secondment of Stephen Kavanagh to Interpol.

The first two men to fill these posts were Lieutenant-Colonel Douglas Labalmondière and Captain William C. Harris respectively.

In 1878, Howard Vincent was appointed Director of Criminal Intelligence, a post that had equal rank to the assistant commissioners, but not the title.

By the end of World War II, Assistant Commissioner "A" (Operations and Administration) was responsible for all uniformed police, including specialist units, except traffic police, which were under Assistant Commissioner "B" (Traffic).

Assistant Commissioner "C" (Crime) headed the Criminal Investigation Department (CID), and Assistant Commissioner "D" (Personnel and Training) was responsible for recruitment, training, welfare, communications and police dogs.

In 1985, Commissioner Sir Kenneth Newman finally abolished the system of lettered departments.

Each assistant commissioner also had force-wide responsibility for a 'portfolio' (such as crime or traffic), setting force policy and managing related headquarters branches.

ACSO remained outside the area system and continued to manage the Specialist Operations units.