Built by amateurs, Prelude was the next step on from Channel class but with her superstructure laid out as Maid of Malham. One radical development that Giles tried on this, his idea of a fast but essentially a cruising boat, was the clever double internal keel construction consisting of a separate wooden girder which in turn supported the keelson and keel and rudder posts.
Built in a shed at Aldershot by a handful of Sapper officers, and with no racing rule in mind she did well around the courses in her first season winning the 1938 Ortac Cup for highest number of points in the small class.