From countersubversion to counter-insurgency – comparing MI5’s role in British Guiana, Aden and the Northern Ireland civil rights crisis

As the imperial security service, MI5 operated throughout the British Empire and in virtually every instance of decolonisation after the Second World War. Using both secondments inside the Colonial Office (Security Intelligence Advisors or SIAs) and representatives within the colonies, dependencies and protectorates (Security Liaison Officers or SLOs), MI5 arguably operated in a more diverse range of political situations than any part of Britain’s armed forces. This article suggests that two main modes of conduct were deployed in the empire’s trouble spots by MI5 – countersubversion and counter-insurgency – and that investigation of these instances can be used to shed light on MI5’s less documented role in the early years of the Northern Ireland Troubles. The article demonstrates that, unlike in Aden, the Security Service managed to maintain their liaison and supervision role in Northern Ireland without being absorbed within the local Special Branch in the first decade of the Troubles.