In 1973, he founded the Mayo School of Astrology, which after his death has operated from Truro, Cornwall. The school, a member of the Advisory Panel on Astrological Education, offers correspondence courses at both certificate and diploma level and issues a list of its qualified consultants who have gained its diploma, D.M.S.Astrol. Diploma holders are eligible to apply for membership to the Association of Professional Astrologers International.
Mayo's background includes engineering and surveying; during WWII he helped make the maps for the invasion of Europe. He was a fellow of theh Royal Meteorological Society and a member of the British Astronomical Association.