national rail line on the Isle of Wight, from Ryde Pierhead to Shanklin (with the Wroxall to Ventnor section closed), was electrified in 1967, so that former London Underground rolling stock could be used, due to the limited height of Ryde Tunnel. The Island Line used 660VDC third rail, as it was a cheaper option to convert the LUL stock into third rail, and implement third rail only on the line. The rolling stock currently used is British Rail Class 484s (D-Train). The line was upgraded to a 750VDC third rail system in 2021 to allow Class 484 units to be used. London Overground to (Watford DC line). Richmond to Stratford (North London line). 750VDC third rail from Richmond to Acton Central. West London line. 750VDC from near the location of the former St. Quintin Park & Wormwood Scrubs railway station to Clapham Junction (shared with Southern services). East London line. Highbury & Islington to New Cross station and the junctions with the South London network near New Cross Gate station and Queens Road Peckham station. Formerly, the East London Line was a much shorter London Underground line with fourth rail 630VDC between Shoreditch (closed 2006) and New Cross/New Cross Gate. See Suburban electrification of the London, Midland and Scottish Railway for Euston–Watford DC Line history. In 1970, the North London DC lines and the Class 501 EMUs used on these services were converted for third-rail operation, with the fourth rail generally being removed on sections not used by London Underground (LUL). Some fourth rail was retained in the Gunnersbury and Queens Park areas for emergency use by LUL. With the closure of Broad Street, the North London line was joined with the Stratford to North Woolwich line; this was electrified with third rail and overhead line as far as Stratford, third rail to North Woolwich. Two branches of the Watford DC line have been closed: to Rickmansworth in 1952 (to passengers, to goods in 1967) and to in 1996. The Watford DC line between Queen's Park and and the North London Line between Richmond and Gunnersbury are used by London Overground trains designed for 750V third rail and Bakerloo line trains designed for 630V third and fourth rail. As a compromise, the nominal line voltage is 650V, and since 1970 the centre rail has been bonded to the return running rail. There are no special provisions required at Queens