He was educated at Shrewsbury School, and Merton College, Oxford.

[1][2] In 1914, on the outbreak of the First World War, Poyser immediately joined up and served with the Yorkshire Light Infantry and the Loyal North Lancashire Regiment.

[1][2] After demobilisation, he began a legal career in the British Empire.

After serving as a puisne judge in Ceylon, in 1939, he was appointed Chief Justice of the Federated Malay States.

In 1941, he resigned to take up the position of Legal Adviser to the Dominions and Colonial Office in succession to Sir Henry Grattan Bushe.