came from the UERL's own Lots Road Power Station on Chelsea Creek. Originally planned by the B&PCR, construction of the power station began in 1902 and finished in December 1904. It became operational on 1 February 1905, generating three-phase alternating current at 11,000 volts, which was converted to 550 volts direct current at track-side transformers located around the network. The power station was constructed large enough to power all of the UERL's lines once they opened plus others later. By the time the last of the DR's steam trains were retired on 5 November 1905, the UERL had spent £1.7 million (£ today) on the electrification of the line. Construction of the tube railways With funds in place, construction of the BS&WR was quickly restarted. 50 per cent of the tunnelling and 25 per cent of the station work had been completed before work had been stopped, and by February 1904 virtually all of the tunnels and underground parts of the stations between Elephant & Castle and Marylebone were complete and works on the station buildings were under way. Construction of the GNP&BR and the CCE&HR began in July 1902 and proceeded quickly so that the UERL was able to record in its annual report in October 1904 that 80 per cent of the GNP&BR's and 75 per cent of the CCE&HR's tunnels had been completed. Following the pattern adopted by the earlier tube lines, each of the UERL's lines was constructed as a pair of circular tunnels using tunnelling shields with segmental cast iron tunnel linings bolted together and grouted into place as the shield advanced. Generally the tunnels followed surface roads and were constructed side by side, but where the width of the road above was insufficient, tunnels were placed one above the other. Stations on all three lines were provided with surface buildings designed by the UERL's architect Leslie Green in a standardised style modified for each site. These consisted of two-storey steel-framed buildings faced with red glazed terracotta blocks with wide semi-circular windows on the upper floor. The stations had flat roofs and were designed to accommodate upward extension for commercial development. Most stations were provided with between two and four lifts and an emergency spiral staircase in a separate shaft. At platform level, the wall tiling featured the station name and an individual geometric pattern and colour scheme designed by Green. The UERL used a