In reply to:

It has told me that Jackie - and presumably others over that side of the pond - pronounce the second syllable of my name as, "man" - whereas I always say, "mahn" in that context.

Jackie (as this avatar of Anu likes to be called) is indeed too sweet for words, however they rhyme. Your noticing the commando difference struck a chord with this Kiwi. That vowel sound is one of the most glaringly obvious distinctions between the accents of those from opposites sides of the Tasman. Australians pronounce dance to rhyme with Manse, while Kiwis "dahnce", and most Kiwis I know cringe (or, as our Aussie neighbours would say, creenge) when they hear the flat Australian a, eh?