After leaving Oxford and spending some time as a private tutor, Blackmore decided on a career in law. He entered the Middle Temple in 1849 and was called to the Bar in 1852. Ill-health, however, prevented him from continuing legal work as a full-time occupation and in 1854, he took the post of classics master at Wellesley House Grammar School, Hampton Road, Twickenham. In later years this became the Metropolitan and City of London Police Orphanage and then Fortescue House School. Soon after accepting this position, he moved from London to No. 25 Lower Teddington Road, Hampton Wick – where he lived until he moved to his new home in Teddington.