A member of the Theosophical Society and close associate of Anna Kingsford. Maitland was brought up in a strict religious family and tended to revolt against the rigid lifestyle imposed on him. He graduated from Cambridge University, and it was intended that he enter holy orders, but he refused to do so. Hearing about the discovery of gold in California, he saw it as a means of escape from the demands made on him by his family and emigrated there, later moving to Australia. In Australia he married, but his wife died after only a year of marriage. He remained away from England for about ten years, returning in 1857. Thereafter, he concentrated on writing for a living, publishing both essays and fiction. In 1875 he published his first book, The Keys of the Creeds. About this time, he met and formed an association with Anna Kingsford, and together they embarked on a campaign opposing vivisection and promoting vegetarianism.

The 1881 publication of their collaborated book, The Perfect Way, resulted in an invitation by Henry Olcott, then president of the Theosophical Society, to join the Society and, further, for Anna Kingsford to become president of the British Branch and Maitland its vice president. This surprising decision was implemented when they were duly nominated by Charles Massey and elected in 1883. Their reign was short-lived because of the opposition of many members who resented their action in introducing "Christian" theosophy, and they resigned from the London Lodge in 1884. Maitland, however, did not resign from the parent society.