When an undersea guided weapon would need replacement

If the Hawker Siddeley Dynamics undersea guided weapon had entered service, would it be due for replacement now?

Only if successive marks kept it current; an essentially unchanged version would probably have been replaced in the 2000s or earlier.

Service life depends on continuous development rather than the original introduction date alone. A Hawker Siddeley Dynamics undersea guided weapon could still be approaching replacement today if several marks and evolutionary upgrades had kept it current. Without that modernization path, it would probably have left service in the 2000s or earlier. Procurement histories must distinguish a maintained weapon family from one frozen initial design.