Born in Luton, Gurney attended Beech Hill Secondary Modern School. He performed his National Service in the Royal Navy, and drove buses and lorries for a living upon his discharge. At the age of 48 he bought his first guinea pig.

Early retirement after a serious accident which left Gurney unable to drive allowed him to devote his attention to guinea pig medicine. Veterinary training did not concentrate on small pets, and Gurney found this sufficient spur to confront and complain about the self regulation of the veterinary profession and highlight its lack of knowledge in the area.

In 1992 Gurney wrote his first book, The Proper Care of Guinea Pigs, during recovery from kidney cancer. During this period, Michael Bond, best known for his Paddington Bear books, met Gurney and encouraged him in his work and writing.

In 1992 he was diagnosed with kidney cancer, and, during his initial recovery, wrote his first book, The Proper Care of Guinea Pigs, taking all the photographs himself. Gurney wrote a number of other books, including The Sex Life of the Guinea Pig, which he promoted on a tour of the United States.

When Great Ormond St Hospital told him that guinea pigs were no longer welcome for health and safety reasons, Gurney complained"[T]hat bunch of control freaks in government took this away from me."

In 2006 he was advised that his cancer had returned and was incurable. He made arrangements to find new homes for his guinea pigs, 40 of whom survived him, before his death at age 68. His final book, Last of Their Kind, was released posthumously in April 2007.

Gurney wrote several books on the health, care and welfare of guinea pigs. He toured the USA to promote The Sex Life of Guinea Pigs.