In the 1980s and 1990s he was successful in the opiate painkiller business, and held appointments at the Laboratoires Pierre Fabre and the Napp laboratories.

Geoffrey Guy was born in 1954 in Stanmore, Middlesex, the only son and the youngest of three of a hospital administrator and his wife, a trainee nurse.

[1][2] During his teens, he attended St Peter's School in Bournemouth, played rugby and was a member of the Air Training Corps.

[1] Following A levels at a sixth form college near Brockenhurst, Guy gained admission to study medicine at St Bartholomew's Hospital, London.

[2] In 1979, he gained a medical degree from St Bartholomew's and in the same year completed his MRCS Eng., LRCP, and LMSSA of the Society of Apothecaries.

[6] He obtained a licence from the UK Home Office to conduct research on compounds found in cannabis that might be useful as medicines.

[19] Guy was a member of the editorial board of the Journal of Cannabis Therapeutics,[5] and has contributed to at least six books and more than 200 clinical studies.