His father was a Charles Newby; not sure of his mothers name as I'm waiting for information on Charles Newby's will from the Western Cape archives, so I don't know if Charles married in England or in South Africa. Charles Newby's parents appear to be a David and Sarah Newby from the Thetford area in Norfolk (border with Suffolk). I can track Charles in the UK census to about 1870 (birth date of 1845), so I assume he came to South Africa in about 1870, 1875. He died in 1894. My great grandmother was born in 1890, so I assume that David was born between 1885 and 1894. I have very little information about David Newby (and my great gran), hence my interest in seeing this topic. I do also have the reference you cited in the previous reply on order. There is a reference to a David John Newby in the South African archives as well.
Thank you for your help!