Graeme,
I suppose the point I'm trying to make is that because 218 was late on the scene, and because the squadron records are mostly missing from where they should be in the National Archives it is very difficult to be precise about the the squadron's beginnings, it's movements, its personnel and its operations.
We do have the combat reports and some accident reports and the abominable "Squadron History" and that's about it. I'm sure the information is there at the National Archive, buried deeply within other reports and documents. It just needs a lot of work to dig it out.
The "catch all" books by Halley, Jeff Jefford and Ray Sturdivant cannot spare the time to dig deeply if the required information is not near the surface, and 218 is most certainly buried.
The fact that Halley's "Squadrons of the RAF" and Ray Sturdivant's "RN Aircraft and Serials" are identical in the area of Squadron movements should tell us something, and I'm not thinking "wow, they both researched it and came to the same conclusion"