This is a Notable Operational milestone.
Alan Marsh was the pilot. Bristol test pilot Charles "Sox" Hosegood also played a role in the development of the type.
This was the first post WWII British helicopter and the prototype for the Bristol 171/Sycamore type series of helicopters. The design was the responsibility of Raoul Hafner who was then the Chief Engineer for the Bristol Aircraft Company's Helicopter Division. The aircraft would become known as the Sycamore by UK operators in the armed services.
Source: "Helicopter Pioneers", Paul Fardink, VFS History Calendar February 2017, VFS web page, Last accessed Jul 27, 2019