Born in Auckland, Kay joined the Royal Air Force in 1926 for a five-year period of service, during which he attempted to break the record for the fastest flight from England to Australia.

This knowledge and experience was helpful when he attempted to break the record of 15 days, 12 hours, for flying from England to Australia in 1930 with H. Piper, another New Zealander serving in the RAF, as a co-pilot.

The duo departed on 9 February in a Desoutter monoplane purchased with funds obtained through the sale of Piper's farm in New Zealand.

In 1934, he competed in the MacRobertson Air Race, a London-to-Melbourne flight, celebrating the centenary of Melbourne, flying a twin-engined de Havilland Dragon Rapide, with two other New Zealanders as co-pilot and wireless operator respectively.

[7] By this time Kay held the rank of squadron leader and was in England, learning to fly Vickers Wellington bombers.

[8][9] On the outbreak of the Second World War, the New Zealand government made the Wellington bombers it had purchased, 30 in total, and the RNZAF personnel receiving training on them, available for use by the RAF.

Despite not being officially formed until 1 April 1940, the squadron commenced operations a few days earlier, flying from RAF Feltwell.

Its first mission was to drop propaganda leaflets over Northern Germany, with Kay flying one of the three Wellingtons involved.

[11] In June, as the fighting in France and Belgium intensified, the squadron carried out several bombing missions to targets on the continent.

[1] Announced in the London Gazette, the published citation read: This officer was captain of an aircraft ordered to attack important targets in the forests south of Bourlers and Baileux during a night in June.

Kay has conducted a number of operations in recent weeks and has shown daring, determination and outstanding ability.Kay was presented with his DFC in a ceremony at Buckingham Palace in September.

[1] Promoted to group captain,[16] he later commanded the Ohakea Air Base in 1944, before moving on to a similar position at Wigram.

[18] In 1951 he became commander of the RNZAF headquarters in London, remaining in the post for two years until returning to the Air Board, this time with responsibility for personnel.

During his time in this role, he oversaw the disbandment of the Territorial Air Force and also ended compulsory military service in the RNZAF.