I can confirm there is no alien technology in the Merlin story, but it is the most detailed description of the design history of the Merlin that has been published so far. The archival research has revealed a lineage of designs and studies stretching back to 1968, many of which have been hidden ever since.
The Admiralty and the Helicopter covers a wide spectrum of projects since 1946 as well as explaining the development of strategy and techniques for using helicopters effectively for ASW and amphibious assault and the sensor technology required the design constraints shipborne operation imposed on the helicopters and the ships. Various torpedo and missile projects are also included, so the book should appeal to anyone who is interested in helicopters, aviation more broadly, naval topics, weapons and projects.