The 1939 Register has him with exactly correct dob, but I cannot pin down the "wife" in 1939 and the (different) mothers of the 2 boys that are in 1939 with him.
1886 Apr 10 Born Middlesex
1915 Married Ethel M Frost in 1915. And she is with him in 1939 Register
1920 Oct 12 Joined RIC no 74262 & ADRIC no 104/102 Porter & ex-Soldier
Posted to C Coy
1921 May 9 to May 24 on Leave
1921 Aug 12 to 28 Aug on Leave
1921 Oct 11 Resigned
1939 Register at 86 Battersby Road, Catford, Lewisham. A Gas Cylinder Skilled Labourer. Wife Ethel M and sons William H J & Arthur F. Oddly the mother of the two boys is a Frost in 1917 and a Dartnell in 1923. It may be that the Dartnell is the wife of William George Lloyd, who may be related to Frederick, and that he is just lodging with Frederick
1955 Jan/Mar died Lewisham