The DH 6 is one of the almost forgotten aircraft of WW1.  It was designed as a training aircraft and used in considerable numbers during 1917.  The intended engine was the 90hp RAF1a but many were equipped with the 90hp Curtiss OX engine.  It proved to be slow and very stable, too much so for a training aircraft, and was replaced in late 1917 by the Avro 504.  However, the German U-boat campaign became successful at this time with considerable losses amongst British coastal shipping.  The DH6 was used as a stopgap, changed to a single-seater and equipped with bombs.  Thirty four flights were established quickly around the coast of Great Britain, five of them manned by the USN.  The slow speed and great stability enabled it to fly in all weathers and it proved successful in its new and unexpected anti submarine role.  The photo below shows a DH6 with the RAF engine and a four bladed prop.  Our two bladed prop is from the DH6 with the Curtis OX engine.

This propeller has been restored and re-polished. It is designed by the Air Department of the Admiralty for use by the RNAS and carries Admiralty Design decals on the blades.  Note that there are scribe marks around the prop as though someone once intended to cut it in two.  

Note also that the person who added the data stamps mis-stamped the diameter as 1520mm whereas it should be 2520mm.