W&SR. The C&SLR soon started construction of its southern extension which opened to a terminus at Morden on 13 September 1926, with a depot south of the station and within of the W&SR route, although no connection was made between the two lines. Without the extension of the District line to Sutton, the additional tracks between Wimbledon and Putney were not required and the work was not carried out. The additional tracks between Parsons Green and Fulham Broadway were constructed, but have only been used as sidings. Once the C&SLR line was opened, the Underground company established a network of bus routes to the south, using Morden station as their hub. These routes had a significant impact on the SR's operations in the area, with the SR estimating in 1928 that it had lost approximately four million passengers per year. The UERL, though, was able to demonstrate that its passenger numbers on its buses to Sutton station were actually more than double those for Morden. Construction Construction of the line from Wimbledon to Sutton was slower. Work started at Wimbledon in October 1927, but property purchases were not completed until the middle of 1928 and the contractor, Sir Robert McAlpine & Sons, did not begin work at Sutton until July 1928. The landscape traversed by the line is undulating and rises from about above sea-level at Wimbledon to about at Sutton. Designed for operation exclusively by the electric multiple unit, extensive embankments and cuttings were constructed and steep gradients up to 1 in 44 (2.27%) and tight-radius curves were employed. Only 35 chains () of the route was built as level track and 24 bridges were required, the largest of which spans over the A24 close to Morden Park. The station buildings at the two end stations, Wimbledon and Sutton, were rebuilt between 1927 and 1930 and six stations were constructed at Wimbledon Chase, South Merton, Morden South, St. Helier, Sutton Common and West Sutton. Fewer stations were built than planned in 1910 and only two of the intermediate stations (South Merton and Sutton Common) were on sites originally planned. With the exception of South Merton, which was built without (being accessed from the road by a long descending staircase), all stations had white stone or concrete-faced buildings, with access to the platforms by stairs up or down from street level. Provided with long island platforms, the stations could accommodate