Born in London in October 1904, John lost an eye when he was two years old. He showed an interest in archaeology from an early age and, after attending Winchester College, went up to Cambridge. 

After university, he travelled to Athens and studied at the British School there. In 1928, he married Miss Milda White, a fellow student. They were involved in excavations in Egypt and Crete, and John became the Curator of Knossos, Crete, in 1929 and the director of the site at Tell-el-Amarna in Egypt in 1930

John was a keen hiker and got to know the island of Crete and its people well, speaking the language fluently.

When war came, he travelled to England to enlist and was commissioned as a captain in military intelligence in 1940. He was sent back to Crete as the British Vice-Consul in Heraklion, where he worked to set up a Cretan resistance network in preparation for a possible invasion.

In October, following Italy's attempted invasion of Greece, John was assigned as liaison officer for the newly arrived British Commonwealth troops and the Greek forces on Crete. 

During the invasion, John was involved with local Cretan forces in the fighting around Heraklion, and on 21 May, he was wounded while engaging German troops south-west of the town.

Uncertainty surrounds the circumstances of John's death.

Most sources suggest that he was taken to a nearby cottage to be cared for by local women while German troops overran the area.

He was given treatment by a German doctor and allowed to remain at rest in the cottage. The next day, new German troops arrived, and finding John out of uniform with no military identity discs, he was executed as a spy. 

He was buried nearby, then reburied by the Germans, before being moved by an Australian War Graves unit to Suda Bay Cemetery in September 1945.

He is buried in Plot 10. Row E. Grave 13. The personal inscription on John's headstone is a line from Percy Bysshe Shelley's poem Adonaïs: An Elegy on the Death of John Keats:

“HE HAS OUTSOARED THE SHADOW OF OUR NIGHT"