Sorry, I wasnt very clear.
Yes I know it is your grandads birth cert you have
THat leads back to Albert and Louisa nee Garner and the marriage in Aylesbury.
That is easy to find on freebmd:
Oct/Nov/Dec 1906
Aylesbury
Ref 3a 1664
Albert Smith / Louisa Emma Garner
That cert can be ordered from
www.gro.gov.ukHopefully you will then have a fathers name and occupation for that Albert.
Does the 1911 Irish census not give ages and places of birth (sorry I am not familiar with it) like the Englisn one? It was Albert and Louisa ages and pobs that I was asking about.
Hopefully that info, plius their fathers details from the marriage cert, will enable you to get back further with the Smiths.
The Garners will be easier - have you looked for earlier records of Louisa Emma? Again based on the age and pob from 1911, if it is given!