Frank H Ferbrache married Phoebe E Evans in the Sep 1943 quarter in St Asaph spans the boundaries of the counties of Denbighshire and Flintshire.
Likely if you found that marriage record it would give you more to go on.
Frank H Ferbrache was born Mar 1921 quarter in Lambeth, boundaries of the counties of Greater London, London and Surrey mothers last name Herbert
Elsie Ferbrache was born Dec 1915 quarter in Lambeth, boundaries of the counties of Greater London, London and Surrey mothers last name Herbert
There was a Gertrude M Ferbrache who married in Dec 1919 who may be an aunt of Frank. There was a James P Ferbrache who married in Mar 1921 to a Thargate. There was a Joseph Ferbrache who married in Sep 1921to a Newman. There was a Lillian Ferbrache who married in Mar 1921 to a Robinson.
There was a William Ferbrach who married in Dec 1907 who is the best prospect for being Frank's father if he married in England. However if the marriage record has the surname misspelled then it would be really difficult to find. Wm was married in Portsmouth and had Violet May in Sept 1909 Maud in Sept 1909 Alice in Sept 1909
they may have just all be registered at the same time and may not be triplets. Wm could have then moved to Lambeth and had Elsie and Frank.