Hi

Is there any actual reason or family oral history or just your own speculation.... dob is often part of Military attesting paperwork ...
In your opening post you gave a wide range of years ... now it seems we may have day and month ... please examine the birth certs and look for each minor fact that was provided by the informant about : herself, and GJF ... address, occupation, age, spelling of each given and family name, localities ... eg does it say married London, England ... or just London ...
And then use your 20 years of genie skills to seek to quietly validate each fact that Mavis provided ... aiming to find what she knew at each point in time ... as that would likely be what she would later tell her three children .. rather than the info GJF provided in 1957 at marriage ....
I understand WA Birth certs can be quite detailed in the 1950s and I stress I AM NOT expecting you to share the details online , but I am simply suggesting how to proceed while you wait for replies from NZ and from MOD in the UK.
JM
Sorry for my two finger e reader typos
