 He studied at Surrey County School (now Cranleigh School) and joined Tetley & Sons in 1872.In 1876, Devonport founded a tea importing company, known as Kearley and Tonge from 1887, and began retailing his own goods in 1878.In 1890, he had over 200 branches trading as International Stores and in 1895, both companies were combined to form International Tea Company's Stores and shares were offered to the public.