Chief of the Secret Intelligence Service

Chief of the
Secret Intelligence Service (MI6)
since 1 October 2025 (2025-10-01)
Secret Intelligence Service
AbbreviationC
Reports toForeign Secretary
Appointer
  • Foreign Secretary
Constituting instrument
Intelligence Services Act 1994
Formation1909 (1909)
First holderCaptain Sir Mansfield Smith-Cumming
Unofficial namesChief of MI6, 'C'
Websitesis.gov.uk

The chief of the Secret Intelligence Service serves as the head of the Secret Intelligence Service (SIS, also commonly known as MI6), which is part of the United Kingdom intelligence community. The chief is appointed by the foreign secretary, to whom they report directly. Annual reports are also made to the prime minister.

The chief of the Secret Intelligence Service typically signs letters with a "C" in green ink. This originates from the initial used by Captain Sir Mansfield Smith-Cumming, when he signed a letter "C" in green ink. Since then the chief has been known as "C".