 Guillemard spent his early career in the civil service, where he was for several years Principal Private Secretary to Sir Michael Hicks Beach, Chancellor of the Exchequer.In May 1902, he was appointed Deputy-Chairman of the Board of Inland Revenue.He was appointed Governor of the Straits Settlements and High Commissioner for the Federated Malay States in 1920, and was one of the promoters of British policies favouring the Malay ethnic group.