[3] He was educated at Christ's Hospital, London and Clare College, Cambridge, where he was sixth wrangler in 1931.
He sat the examinations of the Royal Statistical Society in 1932 and was awarded their Frances Wood Prize.
[4] Clarke worked for the British Electrical and Allied Manufacturers' Association, 1932–33.
Wass stated that, with the exception of Sir Leo Pliatzky, Clarke held most ministers and colleagues "in high disesteem".
According to Sir Sam Brittan, "it was because his round glasses and the bridge over the nose looked like OTTO.