The section of line on which Aberderfyn Halt was located was part of the 1¾-mile Great Western Railway (GWR) Ponkey Branch. The GWR opened the Ponkey Branch railway between Gardden Lodge Junction (on the Shrewsbury and Chester line), furnaces at Ponkey and Aberderfyn and Bryn-yr-Owen Colliery on 1 August 1868. The line was single track and on 27 August 1876 it was extended to Legacy to serve the colliery of this name which was short-lived and had closed the previous year. The 6-inch scale OS map for the area published in 1879 showed connections to Gardden Pit, Brandie Pit and Park pit at the southern end of the line. Just to the south of where Aberderfyn Halt would later be located there was a connection to the Ponkey Brick and Tile Works.
By the time of the publication of the 1900 6-inch scale map a large gasworks had been established on the west side of the line just to the south of the Aberderfyn Halt site.
In 1901 the GWR opened its Rhos branch which passed through Legacy and a connection was made with the Ponkey Branch.
Passenger services were introduced onto the Rhos branch on 1 October 1901 and enhanced through the introduction of a rail-motor service on 1 May 1905. In 1906 a signalbox was provided at the Ponkey level crossing (south of the Aberderfyn Halt site). It was part of improvements that were made to the line between Ponkey Crossing and Legacy to facilitate the introduction of a rail-motor onto the line. The upgrading of the section of line between Ponkey Crossing and Legacy for passenger services seems to coincide with that section of the line being referred to as the Legacy Branch. It appears on maps of that period with that title.
Aberderfyn Halt was opened on 5 June 1905. It was located on the south side of a level crossing that carried the Aberderfyn Road across the line. To date no photographs of the halt have appeared so it is not known what facilities it had. The 25-inch scale map published in 1909 shows a short platform and what is most likely a waiting shelter midway along it. The platform and shelter were most likely of timber construction.
The steam rail-motor service ran between Ponkey Crossing Halt (a short distance to the south of Aberderfyn Halt) and Wrexham General. As well as Aberderfyn it also called at the intermediate points of Fennant Road Halt, Legacy station and Rhostyllen station. The journey overall journey time between Aberderfyn Halt and Wrexham General was 15 minutes which was relatively fast. However Aberderfyn Halt had competition for Wrexham journeys in the form of the Wrexham and District Electric Tramways which had opened an electric tramway between Johnstown (just to the south) and Wrexham on 4 April 1903. Although the trams were slower than the trains they took passengers into the town centre; Wrexham General station was inconveniently located half a mile from the centre.
Despite the tramway competition the November 1906 timetable (click here) showed a generous service of twelve trains in each direction Monday-to-Friday with three additional services on Saturday. Within a few years though the GWR had clearly tired of trying to compete with the trams as the company withdrew the rail-motor service on 22 March 1915. Two years after the passenger service was withdrawn the connection with the Rhos branch was removed and by the 1930s the line had been cut back to a point just to the north of the Aberderfyn Road. The 6-inch scale map of 1938 refers to the branch by its original name (Ponkey Branch).
The Ponkey Branch passed into British Railways ownership in January 1948 and remained in use to serve the Ponkey Gasworks until 31 August 1964.
The electric tramway closed on 31 March 1927.