 As proposed in March 2010, the line would run from London mostly in a tunnel, to an interchange with Crossrail west of London , then along the Acton–Northolt line ("New North Main Line") past West Ruislip and alongside the Chiltern Main Line with a viaduct over the Grand Union Canal and River Colne, and then from the M25 to Amersham in a new tunnel.After emerging from the tunnel, the line would run parallel to the existing A413 road and London to Aylesbury Line, through the wide Chiltern Hills Area of Outstanding Natural Beauty, passing close by Great Missenden to the east, alongside Wendover immediately to the west, then on to Aylesbury.After Aylesbury, the line would run alongside the Aylesbury–Claydon Junction line, joining it north of Quainton Road and then striking out to the north-west across open countryside through North Buckinghamshire, Oxfordshire, South Northamptonshire, Warwickshire and Staffordshire terminating the phase at Lichfield with a connection onto the WCML.