See: "Five-Eyes" agreement: UKUSA Agreement Release 1940-1956 (link). Contains a wealth of background documents. For example, the 1955 version of the 1946 UKUSA Agreement (pdf)
See: “Five-Eyes” agreement: UKUSA Agreement Release 1940-1956 (link). Contains a wealth of background documents. For example, the 1955 version of the 1946 UKUSA Agreement (pdf)