Centenary History Policy on Disclosure

The long-standing policy of successive Governments of all political complexions has been to give a "neither confirm nor deny" response to questions about matters that are sensitive on national security grounds (the "NCND policy"). 

The policy mainly applies to claims or speculation relating to the activities of the security and intelligence agencies. Secrecy is essential if the agencies are to be able to perform their statutory functions effectively. For MI5, the information protected by the NCND policy includes the identities of our investigative targets, the covert techniques and methods we use to investigate them, not least "covert human intelligence sources" (better known as agents), and the identities of serving and former staff. Public disclosure or confirmation of a target's identity, or of the covert techniques and methods used to investigate them, would alert the target to MI5's interest and enable them to frustrate our ability to uncover and disrupt their plans. In the worst case, confirming the existence of an agent or revealing their identity could put lives at risk. The breaking of promises of anonymity given to agents would also be likely to make existing and prospective agents unwilling to cooperate with us. Similarly, disclosing the identities of staff could put them at risk, compromise the operations on which they are or have been engaged, and limit how they could be deployed in the future. 

The NCND policy, reflected in the legislative framework of the Security Service Act 1989, is the starting point for the identification of targets, sources, agents and staff in the centenary History, as it is for all other public disclosures of information relating to MI5. However, the History was a unique venture designed to enhance MI5's ability to protect national security by explaining us and our work to the public that we serve, in the expectation that this will enhance confidence in us and support for our work. In recognition of the importance of the History and its aims, it has been agreed that there is an overriding national security interest in making public in the text, within carefully considered constraints, some matters that would ordinarily fall to be protected. They are as follows. 


The History would not be credible if it said nothing about the groups and individuals who have been the subject of MI5's investigations (we generally refer to groups and individuals of this type as "targets"). The release of historical Service files to The National Archives ('TNA'), which began in 1997, has resulted in the official confirmation of the identities of a significant number of MI5's targets in the period up to 50 years ago. The History of course draws on those files. As for the more recent period, the text explicitly identified as targets certain individuals or organisations, whom it was obvious, from what had already been officially disclosed, must have been the subject of MI5 interest. Given the previous official disclosures, there was no requirement to apply NCND to protect these targets from disclosure. A small number of targets were identified for the first time in the History on the basis that the case for identifying them in this context was so strong, and the direct damage caused by so doing so small, that it was judged exceptionally that NCND need not be applied to protect them from disclosure. 

In the case of target organisations, these disclosures are almost exclusively confined to the naming of senior leadership figures who were the subject of MI5 interest. In every case, the departure was made after very careful consideration, on the basis that it was judged essential to the aims of the History and represented the outer limit of what can properly be disclosed without damaging national security, taking into account the continuing importance of NCND to MI5's ability to perform its functions. 


Information about the identities of agents is immensely sensitive and fiercely protected by MI5, and speculation or claims about the identities of particular agents will invariably be met with an NCND response. A small number of agents of major historical importance have been officially identified in the past in file releases to TNA – notably the Second World War "Double-Cross" agents whose wartime role has received extensively publicity. Their cases are referred to in the History. In addition, a very small number of agents were named there for the first time. The decision exceptionally to name these agents was been taken after the most careful consideration and on the following basis: 

i) there was already very well-sourced information in the public domain about the work done for MI5 by the individuals concerned; 

ii) the individual's role as an agent was judged to be of such historical importance that its disclosure was essential to the aims of the History; and 

iii) the information related to the period before 1945. Regardless of the circumstances or of the historical importance of the case, no agent's identity was disclosed in the text and no information was included from which the identity of an agent might be inferred after the end of the Second World War. 

As for agents (whether of the UK or its allies) who subsequently defected to the West, they were named in the text where both their agent role and subsequent defection had been previously disclosed or acknowledged officially by HMG in an exceptional departure from NCND or by the relevant allied government, or had been disclosed by the defector widely into the public domain. Otherwise, such agents are not identified in the text and the NCND policy continues to apply to them in the usual way. 


MI5's policy is to preserve the anonymity of all living members of staff, whether serving or retired, and the anonymity of deceased staff in relation to the last 50 years (i.e. in the case of the History, from 1960 onwards). The reason is to protect the individuals concerned, their colleagues and families, and to maintain their operational value to MI5 and the security of the operations on which they are or have been engaged. The policy permits the identification of deceased staff in relation to the period more than 50 years ago, as well as the identities of all DGs. Certain limited exceptions from this policy were made in the History so as to permit the disclosure of the identity of a member of staff where: 

i) their membership of MI5 was already so effectively compromised that there was no longer a case for protecting it, or 

ii) the contribution that naming the individual would make to the History's aims was so strong, and the direct damage caused by doing so was so small, that it was judged exceptionally that NCND need not be applied to protect their identity from disclosure. 

The second category is almost exclusively confined to a number of senior members of MI5 employed before 1960 whose employment continued after that date, and whose identities had already received some unofficial publicity in relation to the later period.