A466
From Tardis Wiki, the free Doctor Who reference
The A46 was a road in the south-east of Wales and the west of England. At least in part, it roughly followed the Welsh border with England and the River Wye.
Part of the A466 crossed the Welsh border just south-east of Skenfrith. Followed south, it passed through Monmouth where it intersected with A40. Continuing south, it followed the River Wye, passing through Tintern.
The A466 appeared on Mary Cooper's map of overflow camps in and around Wales. (TV: The Categories of Life)