Originally built in 1937 in the United Kingdom for Thomas Sopwith, she served in the Royal Navy as an armed yacht during the Second World War.

The vessel was built in 1937 by Camper and Nicholsons in Gosport, Hampshire as a luxury yacht for Thomas Sopwith, a wealthy British aviation engineer and industrialist, who was then the chairman of the Hawker Siddeley Aircraft Company.

One of the world's largest privately owned motor yachts of its time, it was intended for leisure cruising and for Sopwith to use as a base at ocean racing events, in which he was a keen patron and participant.

[3] She crossed the Atlantic in the same year for Sopwith's unsuccessful attempt to win the Americas Cup as helmsman of his new J-class yacht, Endeavour II.

In September 1942, Yachting magazine reported that she was "one of the most luxurious warships afloat... her oak-panelled wardroom can seat fifty people at dinner at one table.

Under the direction of the Commander-in-Chief Western Approaches, Admiral Sir Max Horton, Philante, with a staff of ASW experts on board, would provide the practical element of these courses, acting as the commodore of a convoy in exercises involving other warships, submarines and aircraft.

[11] Philante's final contribution was in May 1945, when she was attached to 21st Escort Group with Admiral Horton on board and supervised the surrender and disarmament of 33 U-boats at Loch Eriboll on the north coast of Scotland.

[5] When Prince Carl of Denmark, a naval officer, agreed to be elected to the vacant throne of Norway in 1905 (taking the regnal name of Haakon), he was promised a royal yacht.

After World War II a nationwide appeal was made for funds to purchase a yacht for the respected and ageing king, who had become a truly national symbol through his steadfast resistance against Nazi Germany.

In July 1947, the ship was bought by Norway for 1,500,000 Norwegian kroner (equivalent to 33 142 000 NOK or 3 870 000 USD in 2021)[12] in time for a model to be made and presented to the King at his 75th birthday.

King Haakon inspected the work in progress during his visit to England in November 1947 for the wedding of Princess Elizabeth and Philip Mountbatten, Duke of Edinburgh.