Cunningham Birth

[peb21]

Hello all,  could any one point me in the right direction to find out the details of the birth of a William Robert Cunningham, his D.O.B is 14 JUL 1919  Cork. 
This is my daughter in law's Grandfather, whom found this out today from her Gran who's 96. 
I believe his father David William Cunningham was in the Army and was posted all over the world.  So it's pretty hard to found anything about the family.  William had a brother but her Gran said his name was 'Buddy'?. and there may be a sister as well name unknown. 
The mothers name was Phyllis Blanche Mayhew.  They married in Wandsworth London 1912.   Phyllis dies in 1936, David then marries a Mabel (as her Gran said he was married to Mabel? I cannot find a marriage) Any advise/help would be very appreciated.    Thank you

[hallmark]

https://www.irishgenealogy.ie/en/civil-records/help/what-civil-records-are-on-line

[hallmark]

One could try a Search like this on

https://civilrecords.irishgenealogy.ie/churchrecords/civil-search.jsp

look for siblings

[heywood]

You can order a research copy of the birth certificate for €4
https://www2.hse.ie/services/births-deaths-and-marriages/get-certificates/ordering-certificates.html

Details here
https://www.familysearch.org/ark:/61903/1:1:FB1T-H6P

[dathai]

same man ?
https://www.familysearch.org/ark:/61903/1:1:X7VC-MKF

https://discovery.nationalarchives.gov.uk/details/r/C15084528

[heywood]

London electoral registers
1921 - 39 show
David William Cunningham
Mabel Alice Cunningham in Cambridge Street, Westminster
Would that be him?

In later year, there is also James William Cunningham at the address also.

[heywood]

London electoral registers
1921 - 39 show
David William Cunningham
Mabel Alice Cunningham in Cambridge Street, Westminster
Would that be him?

In later year, there is also James William Cunningham at the address also.

Comparing with 1939 info, I don’t think this is the right family.

[heywood]

Probate record 1937 (death 1936)
Administration for Phyllis Blanche Cunningham, Devon granted to husband, David William Cunningham, Colonel H M Army.

[peb21]

 I think I have David + Mabel for 1939 living in the Sutton area.  Two names blanked out. States he was a Schoolmaster.  I need to get my D.I.L to ask her Gran about this.  I will check into James William Cunningham, I know at one point they were living in the Lambeth area amongst other areas also. 

Thank you for your help...