Davidson was born in 1921 and educated at Portsmouth Grammar School and Christ's Hospital, then at the Royal Naval College, Dartmouth.
His first posting, as a midshipman, was to the old cruiser HMS Hawkins, but in 1942 he was transferred to the destroyer HMS Inconstant, with which he took part in the first successful British landing of the war, at Diego Suarez in Madagascar.
In 1943 he was appointed first lieutenant of the frigate HMS Calder. On escort and anti-submarine duties in the Western Approaches and the Mediterranean, the Calder was credited with sinking three U-boats, and never lost a ship on the fast troop convoys to Malta. In February 1944 Davidson took temporary command of the ship aged just 21.
Shortly after D-Day, Davidson joined HMS Rocket, an Eastern Fleet destroyer which took part in the Battle of Penang. After postwar pilot training, he served as executive officer and first lieutenant on HMS Childers, which took part in the painful and sensitive operation of policing illegal Jewish immigration into Palestine.
In 1951 he was posted as naval liaison officer to the Chinese Nationalist Government. The post was a sensitive one, with the Korean War in progress and the Communist Chinese threatening the offshore islands. The nationalist leader Chiang Kai-shek lived close by and Davidson was invited to the family home to play mah-jong. On his return to England, Davidson was promoted and became commanding officer of the minesweeper HMS Welfare, on minesweeping and fishery protection duties. But he found the peacetime Navy less attractive than wartime service and decided to seek an alternative career.
He married his wife Daphne While in 1955.
After being called to the Bar, he joined the Commonwealth Relations Office in 1960. His first assignment was as first secretary in the newly independent Trinidad. In 1969, though, he was posted to Phnom Penh, where he formed a good relationship with the head of state, Prince Sihanouk.
In 1970 Sihanouk was deposed in a military coup. The British and American embassies were the only ones to keep families on in Cambodia, and the Davidsons were kept awake at night by the mortar fire of the Khmer Rouge closing in on the city. All those who worked for them later fell victim to the horrors of "Year Zero". Davidson was an acknowledged authority on the region and his book, Indo-China: Signposts in the Storm (1979) was well received.
In 1972 Davidson, who had been appointed OBE the previous year, was asked to go to East Pakistan as deputy high commissioner. The India-Pakistan war had just concluded and his first task was to witness mass burials of the victims. He worked closely with Sheikh Mujibur Rahman, the first Prime Minister of the new state of Bangladesh, and he was involved in the negotiations which took place on Indira Gandhi's visit to the new country in March 1972.
The disaster of Bangladesh had attracted much Western aid and, with it, the interest of those looking for a quick profit. Davidson's visitors in Dhaka in the early days included John Stonehouse and Robert Maxwell. Davidson ejected the former from his residence and politely refused the latter's forceful demands that aid money be spent on Pergamon Press publications rather than bailey bridges. He ignored Maxwell's threats of dire consequences from "powerful friends" back in London.
After Bangladesh, Davidson had two appointments as head of mission. The first was in Brunei where, as High Commissioner, he was accommodated in Somerset Maugham's old house. He became a trusted adviser to the Brunei Royal Family during the delicate negotiations towards the new treaty of friendship and, eventually, independence.
His final posting was as Governor of the British Virgin Islands. While there, he gained the trust of the population, who had been extremely hostile to the idea of a British Governor after the recent constitutional negotiations, and he successfully resisted early attempts by organised crime to infiltrate the colony's financial institutions.
He retired from the Diplomatic Service in 1981. After a period as a visiting fellow at the London School of Economics he decided to do a pupillage at the Admiralty Bar. His knowledge of minesweeping and wartime ship design proved unexpectedly helpful during the inquiry into the sinking of the European Gateway.
But it was not practical for him to embark on a career at the Bar at the age of 60, and in 1982 he accepted appointments as legal chairman of Mental Health Review Tribunals and deputy president of the Pensions appeal tribunal, jobs which occupied him almost full-time for the next 13 years. In the mid-1990s he acted as the president of the Pensions Appeal Tribunal, but he declined an invitation to do the job permanently.