Born at Merton in England, in 1788 Wallis travelled to Italy, visiting Rome, Naples where he painted the surrounding countryside, and Sicily. He became a member of the Roman Academy in 1806, and operated as an art dealer in Italy, and later Spain, most often working for British clients. He settled in Heidelberg in 1812, but returned to Italy in 1817 where he taught at the Accademia di Belle Arti in Florence and painted frescoes and portraits. He died in Florence in 1847.