The second son of
physician and
psychiatrist John Elwes Duffield (1910–2009) and his first wife, Jean Edwina (née Stellman), Duffield was educated at
Harrow School and then took a degree in biochemistry at the University of Oxford. After this, he went into investment management and, having become manager of his wife's estates, moved to Switzerland as a
tax exile. He founded
Jupiter Asset Management in 1985. After selling Jupiter Asset Management to
Commerzbank, he founded
New Star Asset Management in 2001. ==Family==