Capes was born in London, one of eleven children: his elder sister, Harriet Capes, was a noted translator and author of more than a dozen children's books. His grandfather, John Capes, had converted to Roman Catholicism, so Capes was brought up a Catholic, and educated at the Catholic college Beaumont College. Capes was a prolific Victorian author, publishing more than forty volumes - romances, mysteries, poetry, history - together with many articles for the magazines of the day. His early writing career was as a journalist, later becoming editor of a paper called The Theatre, which was well known in late nineteenth century London.