Following the death of his father in 1919, the family moved to Cape Town where he attended the South African College School.

[3] His work made an immediate impact and as early as January 1939 he was invited to speak at Hadamard's seminar in the Collège de France.

After leaving Cardiff he spent three years in North America, as visiting professor at Caltech during 1964, followed by a two-year stay at the University of Toronto.

In 1967 he returned to the UK to serve as head of the mathematics department at the newly constituted Chelsea College, University of London, where he remained until his death.

He studied the unbounded operators that arose from quantum theory,[2] extending basic work of Frigyes Riesz and John von Neumann.