The Security Service, also known as MI5, is the United Kingdom's domestic counter-intelligence and security agency and is part of its intelligence machinery alongside the Secret Intelligence Service.
Members[]
Former[]
- John Lancaster † - MI5 Counter-Intelligence Chief under the reign of British Prime Minister James Wilson until his death in 2016. Was killed by MI6 agent Jacqueline Marshall after he refused to turn himself in for his role in the London Siege.