Special Branch (Metropolitan Police)

It maintained contact with the Security Service (MI5) and had responsibility for, among other things, personal protection of (non-royal) VIPs and performing the role of examining officer at designated ports and airports, as prescribed by the Terrorism Act 2000.

[1] Harcourt envisioned a permanent unit dedicated to the prevention of politically motivated violence through the use of modern techniques such as undercover infiltration.

[2] In 1886 its name was changed to Special Branch as its remit had gradually expanded[3][4] to incorporate a general role in counter-terrorism, combating foreign subversion, and infiltrating organized crime and trade unions,[5][6] becoming the largest Special Branch in the United Kingdom.

Although it later became independent of the Criminal Investigation Department (CID), its officers were entitled to use the prefix "Detective" in front of their ranks.

The formation of SO13 had begun a process which on 2 October 2006 culminated in Special Branch and SO13 merging to form Counter Terrorism Command (SO15).