RAF observer silver sweetheart brooch

A wartime period RAF observer's sweetheart brooch. 
The "O" is inlaid with white enamel and the single wing in blue with the outline of the feathers showing through in silver.
The reverse is marked "Silver."
This is mounted on a hollow rounded bar pin, the reverse, also marked "Silver". 
In a very good condition
The enamel is intact with only minor pitting to white.
Size, width = 45mm.

NOT FOR SALE to the EU.