Covert Human Intelligence Sources (CHIS), or “agents”, are people who can provide intelligence that assists our investigations. Agents are not MI5 employees – we refer to our staff as “officers”.
Agents are one of the most significant information gathering assets we have. Agent operations are run by specially trained officers known as agent handlers, and can continue for long periods, sometimes for many years. Intelligence from our agents is critical to keeping the UK safe.
Public views of what MI5 agents do are often based on fiction and not always accurate. There are many misunderstandings about what our agents do, as we cannot say much about those who help us, given our commitment to protect their identity.
However, we can point to an historical example of the vital work that MI5 agents have carried out. One of our most famous agents during the Second World War was Juan Pujol, codenamed "GARBO", a Catalan who volunteered to work for MI5 as part of the 'Double Cross' system. This was a counter-espionage and deception operation directed against Nazi Germany. He worked with MI5 to provide the Nazis with misinformation about British military intentions and played an invaluable part in the war effort. One of his greatest achievements was supporting the D-Day landings by helping to persuade the German High Command that the invasion would take place elsewhere.
Another MI5 agent who helped in the OVERLORD deception was Polish Air Force pilot and former French Resistance fighter Roman Garby-Czerniawski, codenamed BRUTUS. He was the best placed of all our agents for sending over military information. Consequently, as the Germans’ confidence in him grew, he was used more and more and played a large part in the deception preceding OVERLORD. In May 1944 BRUTUS was notionally posted to the non-existent FUSAG (First US Army Group): he passed to the Abwehr a series of messages disclosing the entire order of battle of this shadow Army Group in south-eastern England and, on D-Day itself, the news that it was going into action at any moment independently of the invasion force, buying more time for the real invading forces in Normandy.
All of the work carried out by our Second World War network of agents required meticulous planning and the utmost discretion. We still require these skills today from those who assist us as agents. Agents have helped us to stop many terrorist plots and attacks in the last decade. Although we are not able to publicly recognise individuals who help, it is no exaggeration to say that they really are unsung heroes.
The Today programme on BBC's Radio 4 recently interviewed an anonymous agent about their experiences of working with MI5. You can listen to The role of the covert agent on the BBC website.
The Regulation of Investigatory Powers Act 2000 (RIPA) provides a legal definition of an agent.
Agent operations carried out by MI5 and other organisations specified in RIPA are governed by Part II of the Act and the Covert human intelligence sources code of practice.
Part II of the Act provides a statutory basis for the use of agents and sets out strict rules for their use. Agents must only be used where it is necessary in the interests of national security, for the purpose of preventing or detecting crime, or in the interests of the economic well-being of the UK.
Our use of agents is subject to independent external scrutiny by the Intelligence Services Commissioner, who carries out checks to ensure that we are acting in accordance with the requirements of the law. He publishes regular reports on the three intelligence services' activities under the terms RIPA.