Here are some possibilities:
1907 Qtr 4: Ivor Flook, born Chepstow Registration District
1911 census: Ivor Flook, born Undy, c1908, living with his grandparents William & Eliza Flook, at Common y Coed, Undy, near Caldicot
1934 Qtr 2: Ivor W Flook married Eunice Emma Thomas, Cardiff
1935 Qtr 2: Eunice Maureen Flook, born Cardiff, mother's maiden name Thomas
1940 Qtr 2: Margaret R Flook born Cardiff, mother's maiden name Thomas
1946 Qtr 2: Ivor W Flook married Josephine N Davies, Bedwellty (maybe him???
1973 June: Ivor Flook, born 11 Oct 1907, died in Cheltenham, Gloucestershire, England
I think that you need to look at this birth certificate next?
Merchant Seaman Record: Ivor Warren Flook, born 5 Feb 1906 at "Riggiete" (probably Rogiet, near Caldicot???) But note that the DOB does not match that above!
On the 1911 census, William & Eliza Flook have a daughter Edith, 20 (but she was also 20 in the previous census!!!), single. Could Ivor be her illegitimate son?
There is also a Charles Warren Flook, born in Undy in 1900 Qtr 1!!!
That could be where the confusion of the names arises?