WW2 Royal Navy Officers visor cap

This is a most unusual wartime Royal Navy Officer's cap. The cap has both a British RNVR Officer's name written inside and that of a German Kriegsmarine Officer.

The cap itself is typical of German construction and with gold Kriegsmarine side buttons and celluloid sweat protector. The side buttons have been blackened at some point and a R/N rank device with chinstrap added.

Perhaps the cap was a souvenir or a trophy re-used by the RNVR Officer, or perhaps a replacement cap issued to a POW. Who knows? The change obviously seems to have taken place a long time ago.