Shepard was educated at Heatherdown School, near Ascot in Berkshire, followed by Eton College (also in Berkshire). In 1964, he was commissioned into the Coldstream Guards, after which he joined 21 Regiment Special Air Service (Artists Rifles). His civilian career started at the Charrington Brewery in the East End of London in 1968. In 1975 he joined Sir Ranulph Fiennes and his wife Ginny at the Duke of York Barracks, Chelsea. Between 1975 and 1979, he worked on preparations for the Transglobe Expedition. He went with members of the group to Scotland in 1975, followed by Exercise Greenland in 1976, and the British North Pole Expedition in 1977. On the Transglobe Expedition he travelled with Fiennes and Charlie Burton, and acted as doctor, dentist, scientist and mechanic. Because of family problems, he returned to the UK after the South Pole crossing, and worked in the office in London.