Details of Theodore's baptism on Ancestry:
[http://search.ancestry.co.uk/search/db.aspx?dbid=1558 '''London, England – Church of England, Births & Baptisms 1813-1916'''] > Borough: Barnet > Parish: St. Paul, Finchley > 1906-1914 > Image 25 of 100; Page 25; Entry No. 193: 28 Sep 1908. Theodore c/o Frederick & Hilda Kopp, Warehouseman, of 3 Duke’s Avenue.
From the 1939 National Register on FindMyPast:
RG101; Piece: 0767J; Item: 016; Line: 36; Letter Code: BGBN
16 St. Paul’s Way, Finchley M.B., Middlesex
Hilda KOPP; born 11 Feb 1884; Female; Unpaid Domestic Duties; Married; Schedule 273 (line 36)
Theodore KOPP; born 24 Jul 1908; Male; Company Director Woollen, Single; Schedule 273 (line 37)
+ 1 Closed Record (Line 38)