Dangermouse
what you are overlooking is that before EH101 there was WG34, and that had been pretty much finished as a design as straight replacement for the Sea King. The later need for speciation into different types only came when others started demanding their pounds of flesh in the design.
Naval Staff requirement 6646 was issued in 1977, and the WG34 (with dipping sonar) was submitted in 1978 in response.That design had been worked on a Westland for some years and was close to finalisation. Then some prat had the idea of a joint venture with lots of variants. EHI as a company wasn't set up till 1980, there was massive delay as a new management tier took over, and then proceeded to cripple the design with excess weight
And don't forget that even when the design was finished they f'd up on the actual build. IBM (now part of Lockheed Martin) had to be called in to supervise system integration and eventually became the project leaders.
So you have a project designed by one company, redesigned and crippled by another, with the build split over two contractors (Westland and Agusta) and project managed by another. Its a wonder the thing ever flew