It's 4.30am and the Herefordshire dawn has arrived. Far below me, the River Wye is a silver swathe through high-banked woods. The sky is soft and peach-coloured, the forest a dense, dark jade jungle.

Border town Chepstow blends the best of ancient and modern, a major medieval powerhouse with its Norman castle strategically built along a limestone cliff overlooking the meandering River Wye. Known ...