Electric traction was introduced in 1905 with electric multiple units operating between Uxbridge, Harrow-on-the-Hill and Baker Street. To remove steam and smoke from the tunnels in central London, the railway purchased electric locomotives, exchanged for steam locomotives at Harrow from 1908. In 1910, a seventeen-minute silent film recording was made showing large portions of the journey from Baker Street to Aylesbury and Uxbridge, seen from the cab of a train. The film survives and is publicly available.