On the 1921 census, the only Cyril Francis b.1914 matches the one in Plymouth. There is a Cyril Francis born 1912 Maesteg and living in Bridgend and another b.1915 Blaengarw and also living in Bridgend.
The Cyril Benjamin Francis form the war records, b.1916 Rhondda, Pontypridd
I also looked for Cyril Beale with nothing in Wales on the 1921 census and nothing with Cyril E.
Added:
Cyril Francis . mmn Francis . Jan-Mar 1912 . Pontypridd . 11a . 1342
Maybe illegitimate?
Cyril Francis . mmn True . Oct-Dec 1913 . Bridgend . 11a . 1817
Cyril Francis . mmn James . Oct-Dec 1915 . Bridgend . 11a . 1579