JJ was born in Boulder, Colorado, but moved to London as a baby. During his school years at Fine Arts College, Hampstead, he became heavily involved in acting, and entered the Webber Douglas Academy of Dramatic Art at the age of seventeen. Since completing graduating from drama school, he has appeared in several films as well as gaining a variety of television roles. He can be seen playing the role of Simon Doyle in the television series Poirot, and has also appeared in Northanger Abbey alongside Felicity Jones as well as the televised version of The Ruby in the Smoke alongside Billie Piper. In 2008 he made his theatrical debut in Ring Round the Moon.