Thanks. I did wonder whether the apparent absence might just be because “Mk.IV” was taken as including “Mk.IV” and “Mk.IVA”, but the lack of any direct reference to a Mk.IVA is indicative, I think. The use of a suffix in this manner is fairly (if not totally) unique among British designations; the suffix A on an American type in British service tended to mean that it was obtained under Lend-Lease