SIS or MI6?

What's in a name?

The origins of the Secret Intelligence Service (SIS) are to be found in the Foreign Section of the Secret Service Bureau, established by the Committee of Imperial Defence in October 1909. The Secret Service Bureau was soon abbreviated to 'Secret Service', 'SS Bureau' or even 'SS'.

The First World War and MI1(c)

The outbreak of the First World War in 1914 brought a need for even closer cooperation with military intelligence organisations within the War Office. This led to the virtual integration of the Foreign Section within the Military Intelligence Directorate. Thus, for much of the war, Cumming's organisation was known as MI1(c). This arrangement did not sit well with Cumming - a naval officer who was less than pleased at appearing under the auspices of the War Office.

A return to Foreign Office control

The debate over the future structure of British Intelligence continued at length after the end of hostilities but Cumming managed to engineer the return of the Service to Foreign Office control. At this time the organisation was known in Whitehall by a variety of titles including the 'Foreign Intelligence Service', the 'Secret Service', 'MI1(c)', the 'Special Intelligence Service' and even 'C's organisation'.


Around 1920, the organisation began increasingly to be referred to as the Secret Intelligence Service (SIS), a title that it has continued to use to the present day and which was enshrined in statute in the Intelligence Services Act 1994.

Why MI6?

'MI6' has become an almost interchangeable title for SIS, at least in the minds of those outside the Service. The origins of the use of this other title are to be found in the late 1930s when it was adopted as a flag of convenience for SIS. It was used extensively during the Second World War, especially if an organisational link needed to be made with MI5 (the Security Service). Although 'MI6' fell into official disuse years ago, many writers and journalists continue to use it to describe SIS.