A tunnel believed to have been built in the middle ages was discovered under footpath surfacing after power technicians were installing a new powerline pole in Monmouthshire.

The tunnel was discovered by technicians working for Western Power Development (WPD) in the heart of Wye Valley, an Area of Oustanding Natural Beauty (AONB) near the border between Wales and England.

The team, lead by technician Allyn Gore, initially went to the village of Tintern to move a wooden pole off of a customer’s property. The pole needed to be moved to avoid blocking a footpath.

They initially used technical drawings and survey information and did not find anything unusual about their potential site, so they began excavating. Very quickly, however, they stopped the digging work because they found what the team initially believed to be a cave.

It wasn’t. It was a manmade tunnel that was 4ft tall that ran underneath the footpath following the brook’s route around the Wye Valley. What was amazing is that the tunnel had not been discovered in centuries despite its sheer scale.

It is not shown on any ordinance survey maps since the Valley started being mapped back in the 1700s, and no authority nor local person appeared to have any knowledge of the tunnel.

Given that Tintern Abbey dates back to the 1100s, it could be related to the beautiful medieval building, as well as potentially being linked to Wye Valley’s ironworks, ruins of which have been frequently found in the area.

Tintern Abbey was largely abandoned after 1541 with the Dissolution of the Monasteries by King Henry VIII after he made himself head of the Church of England. This essentially ended the era of huge monasteries that had lasted 400 years as it was seized by the king.

By 1568 the Wye Valley became a home of industrial works, with the Abbey itself even becoming a home for local ironworkers for a time, with small cottages being added to the Abbey’s site.

Eventually, with the rise of tourism in the 18th and 19th century, the Wye Valley became an area known for its staggering beauty and the Abbey itself a landmark reclaimed by nature as ivy grew on top of it.

In 1901 it was bought by the Crown and became a Grade I listed building in 2000.

After the WPD consulted with Cadw (the historic environment service of the Welsh Government) and talking to a representative of the group, all work was halted to avoid damaging or weakening the tunnel whilst the tunnel is investigated further by archaeologists.

Given the unique and fascinating history of the area, as well as all the discoveries found regarding the Abbey itself, there is the potential for some previously undiscovered historic find within the tunnels.

As for the repaired powerline, WPD has prepared an alternative route to wire and move the pole, to avoid disturbing the archaeological investigations set to take place under the footpath.