A section of the former road alignment, some 4km east of Llandovery, lies parallel to and southwest of the present A40 (nprn 419867). It includes Bont Gam, a stone bridge crossing a tributary of the Afon Gwydderig. The former road diverges from the A40 at SN 8022 3505 and runs north-west to south-east for approximately 1.4km, before re-joining the A40 at Llwynwormwood Arms at SN 8092 3412. The current route of the A40 main road is much more gently graded than the former route and had by-passed it at least as early as 1888, as shown on the first edition Ordnance Survey 25-inch map published that year. Near the northern end stands the Mail Coach Pillar (nprn 23522), a stone obelisk erected to mark the mail coach accident of 1835.
Ian Archer & B.A.Malaws, RCAHMW, 17 February 2005 & 12 February 2014.