Magor or Undy troughs were installed (on what became the fast lines) in 1906 some 1.45 km to the east of Magor Station (centre point at 150 miles 21 chains from London Paddington station) and were 510 yards (512 metres) long. On the third (1921) edition of the Ordnance Survey 25in mapping, a rectangular structure, probably a water tank, is depicted at the centre point of the troughs on the south of the line. Along with the troughs at Ferryside (nprn 422808), they were the only troughs installed on the Great Western Railway in Wales.
Sources: The Railway Magazine, May 2018, p.23; railwaycodes.org.uk, accessed 30 April 2018
B.A.Malaws, RCAHMW, 11 May 2018.