This is another case where the broader family story comes as a complete surprise once the initial research starts.
I recently received the Australian Service Medal 1939-1945 awarded to 126436 Vincent Hennessy. I found very little publicly available information about Vincent which wasn't assisted by the NOK details simply being 'M Hennessy'. It took some time and several unsupported assumptions to work out that Vincent's full name was Vincent John Hennessy.
The name 'Vincent Hennessy' only appeared in two electoral rolls from the 1950s. Neither entry indicated Vincent was married so I was really running out of leads. I found 'Vincent John Hennessy' in a couple of Ancestry family trees which seemed to confirm my assumptions. These trees showed Vincent was the son of William and Mary Hennessy. Was Mary the 'M Hennessy' listed as the NOK? A message to Leanne who owns one of the trees confirmed that my assumptions were correct. Then came the surprise.
Vincent was the brother of 437579 FSGT Kevin William Hennessy. Kevin was a crew member of Halifax LL459 which crashed on a night flying exercise on 8 June 1944. The crash occurred near the Yorkshire village of Hook. The entire crew of six died. The links to the crash reports also have pictures of Kevin and his headstone.
Thanks to Pam H who sent me Vincent's medal and also to Julie H who assist me with this research. I'll send Leanne the medal in the near future,
The returned medal tally is 2642.