His birth mother was an Irish nurse who came to work in the United Kingdom during the Second World War.

[4][5] In 1962 he went to study history and philosophy at the University of Southampton, where he developed an interest in acting,[6] and after graduation he joined the Royal Court Theatre.

Following that he had small parts in many TV programmes including The Liver Birds, Dickens of London, Robin of Sherwood and an episode of Enemy at the Door called "Officers of the Law", first broadcast in March 1978.

Following the end of Bergerac, Nettles did five seasons with the Royal Shakespeare Company,[5] appearing in The Winter's Tale, The Merry Wives of Windsor, Julius Caesar, Richard III and The Devil Is an Ass.

Midsomer Murders was an immediate hit, achieving 13.5 million viewers on its launch in 1997 and was sold to more than 200 countries worldwide.

In February 2009, it was announced that Nettles had decided to leave Midsomer Murders after two further series were made.

In 1991, he wrote the semi-autobiographical Nudity in a Public Place: Confessions of a Mini Celebrity (Robson Books; ISBN 0-7451-1961-1) about becoming a "reluctant heartthrob" to female viewers of Bergerac.

In 2012, Nettles wrote Jewels and Jackboots (Hardback ISBN 978-1-905095-38-4) about the German occupation of the Channel Islands.

[citation needed] In 2019, John Nettles published an edition of the diaries of Reverend Douglas Ord during the German occupation of Guernsey during World War 2 (Hardback ISBN 978-1-9993415-0-3).

Their daughter, Emma Martins, was born in 1970,[citation needed] and moved to Jersey with her father for Bergerac.

She joined the States of Jersey Police, working with officers who met her father during the show's filming.