Reeves was born in Sutton, Surrey,and grew up in Suffolk, whose landscape made a deep impression on his best known film, Witchfinder General. His father died when he was young, but his mother was a devoted single parent. As a child he began making short films, some of which starred his lifelong friend, the actor Ian Ogilvy. As a boarder at Radley College he obsessively broke bounds to attend the cinema, and was utterly single-minded about his ambition to work in film. Upon leaving school he turned up on the doorstep of his favourite director, Don Siegel, who promptly employed him as an assistant. Subsequently he worked in Italy, where he was assistant director and writer for Il Castello Dei Morti Vivi with Christopher Lee (1964; also called The Castle of the Living Dead) and La Sorella di Satana (1965; also called Revenge of the Blood Beast and also known in Italy as Il Lago di Satana). The films were made very cheaply, but despite this, La Sorella di Satana was remembered for an appearance by horror icon Barbara Steele, of whose time Reeves was given only four days. Back in London in 1966, Reeves made The Sorcerers, starring Boris Karloff, an effective 'swinging London' picture with supernatural overtones. Both films also starred Ian Ogilvy