I would like one question,why is not included in this part of the E4 Messer?

[41Sqn_Banks]

Originally Posted by Osprey

I suspect it's been said already but that's not true. The Spitfire letter denotes the wing type, A being 8 gun, B supporting cannon, C a multipurpose wing of cannon or mixed 303 and E 50cal + cannon

IMHO the consistent wing type letter system was "applied" late war or even post war.

When the Spitfire I came into service there was only one wing type, hence there was no letter for it. In 1940 the letter "A" and "B" were added to distinguish between the machine gun armed and the canon armed version.
Spitfire II and V used the same system, "A" meaning machine gun armed, "B" canon armed. Then there was introduced the "universal wing" and machines with it were given the "C" letter.
Sounds like the wing type letter system, but then the Spitfire IX with Merlin 60, 61, 63 came in service, and the wing type system wasn't used initially! They all had the "universal wing" but they were simply called Spitfire IX without the "C" letter. When the Spitfire IX with Merlin 66 was introduced they were given the name Spitfire IXB - simply to distinguish between the different engines. Obviously not the wing type letter system.

After this the wing type letter system must have been "applied" retroactively to all marks.