[1] Twentyman-Jones was born in Beaufort West, the fourth of the six children of Alfred George Twentyman Jones, a merchant, and his wife Eliza Arderne.

He scored 33 and 50 (out of totals of just 84 and 80)[4] against the touring Australian cricket team on a bad pitch[5] and was picked for the third Test match at Cape Town immediately afterwards.

[11] As a member of the bar, Twentyman-Jones practiced in Cape Town and built up a good reputation and was particularly strong in criminal law.

[3] He co-authored with H. O. Buckle the well-known legal textbook The Civil Practice of the Magistrate's Courts in South Africa and also authored several other books, including one on The Cape liquor laws.

[2] His daughter passed his legal and other papers to the University of Cape Town Library in 1976: they include photographs of South African cricket teams from the 1880s and later.