He visited the Middle East and Turkey, but had to break off his trip in 1939 at the beginning of World War II.
Immediately after he was demobbed, Davis moved to Scotland to study botany and biology at the University of Edinburgh.
His proposers were Sir William Wright Smith, Alexander Nelson, John Anthony and Brian Burtt.
He later received the Gold Medal of the Linnean Society of London for his commitment to the Royal Botanic Garden Edinburgh.
Under the terms of his will he endowed the Davis Expedition Fund, to assist Edinburgh students to undertake biological fieldwork abroad, as he had done.