[Nick Beale]

I think you have to accept that the Osprey Aces series allow themselves a flexible defintion. If they didn't you sometimes wouldn't have a book at all. In the RAF, my understanding was that no official score totals were maintained (although IIRC numbers destroyed were sometimes given in press releases and award citations) and there was no formal "ace" status, so Osprey have some editorial latitude.

I buy their RAF/Commonwealth books for a compact overview of operations by the type of aircraft concerned. With a manageable topic like the Typhoon/Tempest or Griffon Spits the 96-page format works well. Personally I'm not that bothered by scores and rankings, especially when "confirmed" victories don't always hold up against the historical records now available, so Osprey can "cheat" if they like!