I once had the privilege of remounting a DSO group for the son of the recipient. His father won an immediate DSO as a pilot officer, when he was the pilot of a Beaufighter which ditched in the sea off the North Cornish coast. The full story is here
https://www.facebook.com/media/set/?...9267011&type=3
Incidentally the medals are illustrated as I mounted them about 30 years ago. It was my first attempt at court mounting and it took me an age!
A.B.Harvey, as he was always known, was a Cornish boy and post war he opened and ran a gun shop in Falmouth. In many years of being involved in medals I have never seen another DSO to a pilot officer, and the details of Harvey's action would seem to support the idea that it was only awarded to junior officers who had just "missed" a Victoria Cross recommendation.