During Britain's punitive 1868 Expedition to Abyssinia, Speedy's knowledge of Ethiopia was crucial to the commander, Sir Robert Napier.
After an audience with Queen Victoria, Speedy was appointed guardian to Prince Alemayehu Simeon, the young son of the late Emperor Tewodros II, who had committed suicide rather than surrender to the British.
He resigned in 1873 to raise and command a body of Indian troops to restore order in Larut, a mining district in the Malayan state of Perak, for the Mentri (Chief Minister) Ngah Ibrahim.
In 1874, Speedy was appointed assistant British Resident of Larut and established the town of ‘Thaipeng’, meaning 'Heavenly Peace'.
In 1883–85, Speedy took part in the mission led by Vice-Admiral Sir William Hewett to the court of Emperor Yohannes IV of Ethiopia to negotiate the region's disputed borders.