Blyth first studied at the University of Otago before arriving at Pembroke College in 1956. At Cambridge, he was a PhD student and later lecturer at the University and the Tutorial Bursar and Assistant Tutor for the College. His work as an academic was primarily on economics of New Zealand and South Pacific islands. He worked at various universities and economic associations throughout his career including the University of Auckland and the New Institute of Economic Research. He died in 2012 aged 85.