24 September, reducing the travel time around the circle from seventy to fifty minutes. By September, after withdrawing services over the unelectrified East London Line and the east of East Ham, the District were running electric services on all remaining routes. From December 1905 the L&NWR service was hauled by electric locomotives from Mansion House to Earl's Court, where a L&NWR steam locomotive took over. In 1907 the weekday off-peak service was four trains per hour from East Ham to Ealing Broadway, four per hour from Mansion House to alternately Richmond and Wimbledon and two per hour from Wimbledon to High Street Kensington and Ealing Broadway to Whitechapel. Four trains per hour ran from Putney Bridge to Earl's Court, two continuing to High Street Kensington. From South Harrow there were two trains per hour to Mill Hill Park, and four trains per hour from Hounslow Barracks to Mill Hill Park, two of these continuing to South Acton. Meanwhile, the UERL's GNP&BR tube railway was under construction, surfacing west of West Kensington and entering two terminal platforms on the north side of the District's Hammersmith station. A new station, Barons Court, was built with two island platforms, one for each railway. As there was space at Lillie Bridge Depot after the District had moved to Mill Hill Park, the GNP&BR took over part of the site for its depot. Barons Court opened 9 October 1905 and the tube railway opened as the Piccadilly line on 15 December 1906. London Underground, 1908–1933 Running an electric railway In 1908 the UERL and the other underground railway companies in London came to a joint marketing arrangement that included maps, joint publicity and combined ticketing. UNDERGROUND signs were used outside stations in Central London. The UERL eventually controlled all underground railways in London except the Waterloo & City Railway, the Metropolitan Railway and its subsidiary the Great Northern & City Railway, and introduced station name boards with a red disc and a blue bar. 'Non-stop' working was introduced on the District in December 1907. Usually just a few stations were missed; trains were marked NON STOP or ALL STATIONS as appropriate and panels beside the doors listed the stations the train would skip. East of Bow Road station the District shared the tracks with steam engines and widening the railway to East Ham was considered essential. Four tracks were laid and two electrified as far