 In 1907, the LNWR obtained parliamentary permission to improve its mainline services into London by the construction of a pair of new electrified tracks alongside its existing line between Watford Junction in Hertfordshire and Queen's Park, Kilburn and a new tube section beneath its lines from there to its terminus at Euston. At Euston, the tube tunnel was to end with an underground station on a 1,450-metre (4,760 ft) long loop beneath the mainline station.
