A Swedish king as a British Royal Navy Admiral

The official photograph of King Gustav (dressed as a Royal Navy Admiral) and Queen Victoria, taken at the Windsor Castle during the Royal visit in 1908. 

Traditions have been - and still are - of particular importance to the British armed forces. The custom of the Royal Navy to appoint foreign royals to be honorary Admirals is one such tradition, although nowadays very sparingly used. 

When King Gustav V of Sweden together with his wife, Queen Victoria made an official state visit to Britain in the fall of 1909 (less than a year after the king had taken office) he arrived dressed as a British Admiral of the Fleet. 

The arrival ceremony in Portsmouth.

The Swedish royal couple arrived in Portsmouth on board the British Royal Yacht Victoria and Albert.

PS

Also the present King of Sweden, Carl XVI Gustaf, is an Honorary Admiral of the Royal British Navy, although I have not seen him wear the uniform.