Since it was signed in 1971 I'd say its been around through all sorts of iterations of UK defence "policy" - UK Govts can and have done what the hell they like
According to Wiki it's surely consultative:-"Signed in 1971, the FPDA consists of the five powers consulting each other "immediately" in the event or threat of an armed attack on any of the FDPA members for the purpose of deciding what measures should be taken jointly or separately in response. There is no specific commitment to intervene militarily, and the agreement is merely consultative. The Five Powers Defence Arrangements do not refer to
exclusive economic zones (EEZ), and the enforcement of a state's EEZ rights is a matter for that state, which may request the assistance of other states in so doing.
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