William was educated at the Leys School, Cambridge; at Bath; and at St Bartholomew's, Hospital - entering as a student in 1909, he obtained the diplomas of M.R.C.S., L.R.C.P. in 1912. He then served as house-physician to Dr Howard Tooth. On the outbreak of war he joined the R.A.M.C. as a temporary Lieutenant. He entered the war in France on 12th November 1915. William was the elder son of Mr W W Thompson of 3 The Avenue, Brondesbury.