During World War II he became a coastwatcher, playing a significant role in the Allied fightback in the Pacific Theatre by providing intelligence on Japanese operations around Bougainville.

[1] He attended Fort Street High School, but moved overseas in January 1916 at the age of 14 to work with his half-brother Tommy,[1] becoming a plantation and trade store manager in the Shortland Islands when he was only 15.

Mason and others fled northwards through the jungle to avoid capture, travelling shoeless, wearing just shorts and a singlet and carrying only a small rucksack and pistol.

[1] Although Mason returned to Bougainville in November 1943, he was forced back to Australia the following March due to contracting pneumonia during an unsuccessful mission to Treasury Island,[1] after which the Japanese began spreading rumours they had killed him.

[1] He was subsequently also awarded the British Distinguished Service Cross and promoted to lieutenant commander in the Naval Reserve (Special Branch) in December 1951.

[1] In the 1961 elections Mason contested the European New Guinea Islands seat, defeating the United Progress Party candidate W. Meehan to become a member of the Legislative Council.