It was during the German Occupation of the islands that that the Cup itself was at its greatest risk because the Germans wanted it to be returned to their homelands to be melted down for funds for the Third Reich. The Cup then mysteriously disappeared, but was safely hidden and resurfaced after the war in 1947. To this day, there is much speculation about where it went during this time but the truth is, nobody really knows.

The actual Siam Cup is a large circular rose-bowl made from Siamese (Thai) silver, beautifully decorated in traditional Siamese style, with figures of dancing girls and elephant heads. It stands on an ebony base and is engraved with the cup winners names, dating back as far as 1920.

The Cup was originally brought to Guernsey by a Lieut-Colonel C H Forty who was serving in the Durham Light Infantry in Siam at the early part of the twentieth century. Forty along with four other colleagues, donated the trophy to encourage interest in the game of Rugby, on hearing that Rugger was no longer played between Victoria College in Jersey and Elizabeth College in Guernsey. The story goes that Vajiravudh, son of the King of Siam, also served in the Durham Light Infantry and was befriended by Forty and Capt S P Groves, another donor of the Cup. Vajiravudh later became King Rama VI and it seems certain that it was he that instructed that the Cup be made from Ticals (Siamese silver dollars) by the Court silversmith.