Sir Patrick Walker (born 1932) joined the Security Service in 1963, following a period of service in the pre-independence government of Uganda.
He led the section responsible for counter-terrorism before being appointed as Director General at the end of 1987. During his term of office he oversaw the Service's transition though the end of the Cold War. The Service was also put onto a statutory footing for the first time through the enactment of the Security Service Act 1989. He retired in February 1992.