The Act specified that the bridge was to be built on the site of the existing ferry "or as much lower down the river as the Commission can settle". Local residents lobbied for it to be built at Water Lane, a short distance downstream from the ferry site. The approach to the river was relatively flat, avoiding the steep slope to the existing ferry pier on the Surrey bank. However, the Dowager Duchess of Newcastle refused to allow the approach road on the Middlesex bank to pass through her land at Twickenham Park, and the commission was forced to build on the site of the ferry, despite a steep 1 in 16 (6.25%) incline.