A Biggles detail

I expect most of the fandom probably already knows this, so feel free to think I'm silly for taking so long to figure it out! But I decided I'd post it here just in case anyone else writing for the series was confused about this (like me!).

It honestly took me the longest time to figure out where the Air Police work out of. Sometimes they're obviously at Scotland Yard; sometimes they're obviously at an airport; and I think I've actually been extremely inconsistent about this when I was writing. Eventually I figured out that there were two distinct locations, but I still couldn't figure out (or remember) what to call them to distinguish between them, since I kept thinking they were both called Headquarters (which, actually, they are). It was just in the past week or two that I went through enough opening scenes of the books, trying to figure it out, to finally nail down the difference.

In Buries a Hatchet, they land somewhere outside of London and head directly inside:

"He looked about him curiously as with the others he walked into the Air Police Operational Headquarters."

vs:

"The only sound in Air Police Headquarters at Scotland Yard was the dry rustle of paper ..."
[Takes it Rough]

Operational Headquarters is at an (I think possibly unspecified?) airport outside the city; regular headquarters - their office - is at Scotland Yard.

I don't know why I had so much trouble with this, but at least now I know! (I know some of what I've written is terribly inconsistent, but I don't think anything is absolutely *broken*, since they could be at either place. I think the one detail I have potentially messed up on due to my confusion about this is that I don't think Raymond has an office at their Ops headquarters - pretty sure all the Raymond office scenes are Scotland Yard only - but I also don't recall if I've ever unambiguously placed him in an airport office anyway ...)

Update: And now I'm thinking about Buries a Hatchet tags and missing scenes again. As you do.