This leaves in the order of 13,000 active files on United Kingdom citizens. To place it in context, this compares with about 5.7 million records on individuals on the Police National Computer. Of those 13,000 files, more than half are for individuals who have come to the Service's attention in a terrorist related context, while the remainder relate to the Service' s other fields of investigation, such as espionage, proliferation and serious crime. A proportion of these files are for individuals who are co-operating with the Service against these threats to national security. Following the collapse of Soviet Communism and the decline in the threat from subversive groups, the Service scaled down its counter-subversion work over a number of years to the point where it is no longer running any investigations in the field of subversion.
Detailed criteria govern the opening of files on individuals and organisations.
These criteria specify the circumstances in which opening a file and initiating inquiries are justified within the terms of the Service's statutory functions. They are kept under continual review and are formally checked on an annual basis for currency, relevance and propriety.