The British in the late 1950s were in a race along with everyone else to produce the next generation of jet fighters and bombers. So test aircraft were built for very narrow technological purposes. The Handley page 115 was one such plane. In fact its narrow mission was to compile airflow data over delta wings at low speeds. It was also a way to test thin delta wings instead of the stubby wing design currently under test in major air faring nation in the world. From 1961 to 1974 the plane put up 500 hours and much valuable data. The aircraft was begun by Miles, and during a an economic collapse had to be taken over by HP.
Sources: The Complete Encyclopedia of World Aircraft. Barnes and Noble