Thanks for the info, Shiner.
Someone sent me a photo showing 47 Squadron and Collishaw in this same hybrid uniform (pictured above) clearly dating it to South Russia in 1919.
In a post that was lost when this thread was moved from the RAF category to here, Zob wrote:
They had a habit in the early transition period of converting older pattern badges to make up what they thought the new RAF badge was supposed to look like. Co of 10 Naval Sqn and later 47 Sqn RAF in Russia.
Zob raises there an interesting point about "transition" periods and availability. I have been told that all shortages of RAF uniform bits would have been resolved by 1919, especially for some one as senior and celebrated as Collishaw. If the CO wants to know what the new RAF badge looks like he only has to look at the fellow next to him.
I cannot believe that in 1919 Collishaw CB, DSO & Bar, OBE, DSC, DFC couldn't lay his hands on a single RAF cap badge by mid 1919 to conform with regulations.
But in the photo there are officers dressed in a range from unadapted RNAS uniforms to complete and up-to-date RAF uniforms. So there is still vanity badging going on and a pretty extensive wearing out period despite what must be a very official desire by the RAF to see everyone looking uniform especially in the postwar period.
So it seems proof positive that Collishaw dressed this way because he wanted to and it was tolerated, at the very least in Russia, and wherever that studio portrait was photographed.
Therefore Collishaw is proof positive of some unofficial, or semi-official distinctive element, from that period 1919 to 1924 (or pre-FAA) for an ex-RNAS pilot.
Back to the Gieves cap that began this post...
Best hypotheses so far, in what I think is descending order of likelihood...
1. 1919-1924 distinctive worn (or tolerated!) by ex-RNAS?
2. RAF on attachment to RN?
3. RN officer attached to FAA pre 1937?
4. 1924-1937 FAA of the RAF?
Or the cap could be humped-up to deceive.
Collishaw opens the door to proof that in some quarters a distinctive which departed from the RAF regs was tolerated early on postwar. I'll be back with a date on that Gieves label which will lend credence or eliminate #1.
Could someone else weigh in on their opinion of the RN portion of the badge, whether the bullion is early or late? Then we'll know if it belongs on that hat.
Rgds