شركة النفط الأنجلو-إيرانية
In 1913 he was sent by Winston Churchill to investigate purchasing a 51% stake in the Anglo-Persian Oil Company. The expedition gave a positive report and the British Government bought a 51% stake in the Anglo-Persian Oil Company just before the outbreak of the First World War. As part of the agreement the Government had the right to appoint two directors, and Slade became one of these, a position he held until his death.