A "secret" medieval tunnel system has been discovered by electrical technicians in south Wales.A team working for Western Power Distribution made the discovery while moving an electrical pole near Tintern, in the Wye Valley, Monmouthshire.Western Power said the tunnels, near to 12th Century Tintern Abbey, were not shown on any Ordnance Survey map.After consultation with Cadw, the energy firm has stopped all work to allow archaeological investigation. "Shortly after the excavation work began, the digging team made the extraordinary discovery of what they initially thought to be a cave."Mr Gore said "work stopped immediately", adding: "I have been involved in...