Brentwood station was opened on 1 July 1840 as a temporary terminus by the Eastern Counties Railway (ECR) on what was to become the Great Eastern Main Line, until 1843, when the line was extended towards . From opening, a small railway turntable was provided and by 1845 as the size of locomotives grew a larger turntable was provided. As it is located at the bottom of a steep incline locomotives were allocated at Brentwood to assist trains get up the bank and by 1868 the turntable was enlarged. A three-track engine shed located at the London-end of the station behind the then London-bound platform of the two-platform station.