Hello Anthony !
I have an Irish grandfather with the exact same lineage and have come up with a blank on his birth certificate too.
I have all the documents from the Birmingham Registrar going back to his marriage to Winnifred Mary Hewson and I have paid a genealogy firm to research Grandfather Hannon, but without any success.
My mum was your Auntie Kathleen, sister of my Auntie Rosie. Your mother, if I have the right person!
I have not seen you since I was about 12 or so when you visited us not long after you had joined the para's,I believe.
If you would like to collaborate on this research then please send me an email to igair57@gmx.co.uk and we can exchange details.
Best wishes,
Ian Greenfield.