Royal Navy HMS Iron Duke pennant flag sweetheart brooch

A scarce First World War period gilt and enamel HMS Iron Duke naval flag sweetheart brooch. Very good condition, original pin fittings, no damage to the enamel.
Width 32mm.
Height 21mm.
HMS Iron Duke was a Royal Navy battleship named in honour of Arthur Wellesley, 1st Duke of Wellington, launched in 1912, she participated in the Battle of Jutland and for a short time the flagship of Admiral Sir David Beatty, later being sold and broken up for scap in 1948.