Several schemes for the construction of a canal to transport coal from the bell-pits on Cockfield Fell to the Darlington market were proposed - the earliest from Robert Whitworth in 1768. John Rennie surveyed the route in 1813 and concluded that a waterway would be viable, from both engineering and financial standpoints. However, in 1818, the Welsh engineer George Overton convinced the residents of Darlington to back a railway, with Parliamentary Assent finally achieved on 19 April 1821.

Yet even before the Bill had made its tortuous way through Parliament, the influential Quaker, Edward Pease, announced concerns over Overton's survey and arranged for George Stephenson to review the route. By the end of 1820, Stephenson had submitted a modified scheme. With some sections of the revised route were outside the limits of deviation imposed by the original Act, a further application for parliamentary approval was made, including powers for the Haggerleases branch, at the western end of the system. This would eventually run from St Helens, near Bishop Auckland in Co. Durham, to its terminus at Butterknowle, some 8 km (5 miles) away, following the course of the River Gaunless.

A second Act of Parliament was granted on 17 May 1824 and the railway was opened on 1 October 1830 to serve the complex of collieries and coke ovens that had emerged at the head of the valley. Originally operated by horses, it became steam powered in 1856. Passenger services became available two years later, but were withdrawn in 1872. By the time the line closed in 1963, the declining reserves of coal made operations no longer commercially viable.

Near the end of the branch at Butterknowle, it was necessary to cross the river on a skew. A skew railway arch had only been constructed once before, by George Stephenson at Rainhill. The resulting stone bridge is notable for its exceptionally low span of just 2 m (7 ft). The skew angle is 27 degrees and every stone used in the construction of the 19 foot arch had to be cut to that angle. The bridge was built in 1830 to a design of Thomas Storey by James Wilson of Pontefract.

The bridge was described thus by W.W. Tomlinson in his History of The North Eastern Railway (1914 - see Bibliography): 'Grit sandstone, coursed and squared with tooled ashlar dressings. Skew plan at angle of 270 with river. Low segmental arch with chamfered voussoirs and wider-arched fall roll-moulded dripstring; this merges with similar string at rail-bed level. Parapets sweep out to round piers and have chamfered coping continuous with top bands of piers, which have low ogee-domed coping. Moulded rectangular inscription panel on north face. One of the earliest surviving skew arches, which were becoming a necessary part of railway engineering.'

The bridge was a controversial element of the engineering plan, with many predicting that it would prove capable of carrying heavy rail traffic. In fact, when the wooden building-supports were withdrawn, the bridge settled by less than 12.5 mm (0.5 in) and it remained in regular use until 30 September 1963, when the section west of Evenwood Colliery was closed. Still standing, the structure is Listed Grade II. Much of the track of the line through the Gaunless Valley can be walked by footpath.