Following up on Genene, there is this marriage:
Marriage Jun 1925 Marylebone 1a 1329 
Buckley    William A R    Coelen       
Coelen    Eugenie M J    Buckley
Maybe Eugenie preferred to be called Genene.
Birth June 1905 Uxbridge 3a 39
Coelen    Eugenie J M
In 1911 Eugenie (b. 1905) is with her parents, Gerard F J H Coelen and Marie A G V Coelen. Her parents were born in Holland (maybe where the South Africa connection came from - surname/accent??)    
The 1939 entry (William Buckley/Genene Mackenzie) has her birth as 20th March 1908.
However, The Daily News (London) dated 24 March 1905 has this birth announcement.  "COELEN - 20th March, at The Warren, Northwood, Middlesex, the wife of Gerard Coelen, of a daughter".  Same address as 1911.
Eugenie can also be found in 1921 with her widowed mother as guests at a hotel in Pembridge Square, London.
I'm still looking but will post this for your thoughts.