 The track gauge was authorised by the Act to be either broad or narrow (later known as "standard gauge"), but the Great Western Railway main line at Cholsey had just been converted from broad gauge to mixed gauge, so the decision was taken to build the Wallingford and Watlington line to the narrow gauge.It was to be the first branch off the GWR's main line to be made on the narrow gauge.First proposals were to construct Wallingford station adjacent to the market place, but in fact it was located on the southern margin of the town.