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 the Security Service, the information protected by the NCND policy includes the identities of the Service's investigative targets, the covert techniques and methods it uses to investigate them, not least its "covert human intelligence sources" (better known as agents), and the identities of its 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 the Service's interest and enable them to frustrate its 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 the Service. 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 History, as it is for all other public disclosures of information relating to the Security Service. However, the History is a unique venture designed to enhance the Service's ability to protect national security by explaining the Service and its work to the public that it serves, in the expectation that this will enhance confidence in it and support for its 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.
The History would not be credible if it said nothing about the groups and individuals who have been the subject of the Service's investigations (we generally refer to groups and individuals of this type as "targets"). The release of historic 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 the Service's targets in the period up to fifty years ago. The History of course draws on those files. As for the more recent period, the text explicitly identifies as targets certain individuals or organisations, whom it is obvious, from what has already been officially disclosed, must have been the subject of Service interest. Given the previous official disclosures, there is no requirement to apply NCND to protect these targets from disclosure. A small number of targets are identified for the first time in the History on the basis that the case for identifying them in this context is so strong, and the direct damage caused by so doing so small, that it is 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 Security Service interest. In every case, the departure has been made after very careful consideration, on the basis that it is judged essential to the aims of the History and represents the outer limit of what can properly be disclosed without damaging national security, taking into account the continuing importance of NCND to the ability of the Service to perform its functions.
Information about the identities of agents is immensely sensitive and fiercely protected by the Service, 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 text. In addition, a very small number of agents are named here for the first time. The decision exceptionally to name these agents has been taken after the most careful consideration and on the following basis:
i) there is already very well-sourced information in the public domain about the work done for the Service by the individuals concerned;
ii) the individual's role as an agent is judged to be of such historical importance that its disclosure is essential to the aims of the History; and
iii) the information relates to the period before 1945. Regardless of the circumstances or of the historical importance of the case, no agent's identity is disclosed in the text and no information is included from which the identity of an agent may 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 are named in the text where both their agent role and subsequent defection have been previously disclosed or acknowledged officially by HMG in an exceptional departure from NCND or by the relevant allied government, or have been disclosed by the defector widely into the public domain. Otherwise, such agents are not identified in the text and the NCND policy applies to them in the usual way.
The Service'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 fifty 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 the Service 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 fifty years ago (pre-1960), as well as the identities of all DGs. Certain limited exceptions from this policy have been made in the History so as to permit the disclosure of the identity of a member of staff where:
i) their membership of the Service is already so effectively compromised that there is no longer a case for protecting it, or
ii) the contribution that naming the individual will make to the History's aims is so strong, and the direct damage caused by doing so is so small, that it is 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 the Service employed before 1960 whose employment continued after that date, and whose identities have already received some unofficial publicity in relation to the later period.