Following my mother's recent death I now have my father's birth certificate and his brother Albert's baptism certificate which confirm my grandmother's surname to be O'Flaherty rather than Flaherty
These list my grandmotherss name as Mary and Mary Elizabeth O'Flaherty respectively.
My grandfather is listed as Louis and Lewis respectively.
They lived at 17 Sumner St, Liverpool at the time.
I have no doubt that we are cousins as I remember both you and Trevor, though I have to admit, it is now quite vague.