The LPTB in collaboration with the LNER and GWR examined ways in which the now-heavy suburban business in Middlesex might be handled, and a scheme was formulated which became part of the 1935 – 1940 New Works Programme; the GWR would build new electrified tracks from North Acton, on the Ealing and Shepherds Bush line, running alongside the Joint Line as far as Denham. The authorising Act was secured in 1936 and by the outbreak of World War II the new track was ready as far as Greenford. Work was suspended during the war, and in fact the new track was lifted and used for emergency purposes elsewhere.