I believe Royal Navy gave up Senior Rating pilots long time ago - Jenkins
I cannot confirm the earliest date from which rating pilots flew as Petty Officer Pilots - so over to Kew? However, of the fifty-five Fleet Air Arm pilots who flew at least one recognised operational sortie during the Battle of Britain, three were Petty Officer Pilots. In 1948, rating pilots in the Royal Navy were commissioned if otherwise qualified, reverted to their source branch, or left the Service, and the rating of Petty Officer Pilot ceased to exist.
Here's the obituary of a particularly interesting and distinguished former Petty Officer Pilot:
Lieutenant-Commander Bill Filer - Telegraph
and, before anyone queries the badge worn in the second photograph, it's apparently a Royal Canadian Navy Clearance Diving Officer's badge, presented by the RCN - probably being worn unofficially, but who would deny someone with his record.
Incidentally, I believe that a number of WRNS ratings were enrolled as Observers - in
early 1918!
Jack