Lowering people down by rope is the only way to prevent ivy, moss, weeds and young saplings getting into the masonry joints and damaging the impressive structure, which is the longest tunnel on the whole length of the canal.
Also known as Savernake Tunnel, after the forest it runs beneath, the structure will celebrate its 205th birthday this year, and is one of the historic highlights of the Kennet & Avon Canal. At 500 yards long, it was built when the local landowner, Thomas Brudenell-Bruce, then Earl of Ailesbury, refused to allow the canal company to mar the view from his nearby home. Rather than having a flight of locks take the waterway over the hill, the Earl instead insisted that the great canal engineer John Rennie adapt the plans and construct a tunnel.
Earl Ailesbury was a prominent courtier at the time, serving as treasurer to Queen Charlotte, having previously been King George III's Lord of the Bedchamber. A plaque at the tunnel's eastern portal commemorates its construction and the ‘uniform and effectual Support' of the Earl.
David Viner, heritage advisor at the Canal & River Trust, said: “The Bruce Tunnel is the longest tunnel on the Kennet & Avon Canal, and a fantastic historical site to have right at the canal's summit. These kinds of works are essential to taking care of it. Left to the elements, woody plants and climbers like ivy would do considerable damage to the brickwork over time.
“The tunnel itself is a classic example of early NIMBYism, where the Earl was clearly only worried about his view. It certainly would have made life harder for those making their way along the waterway- there's no towpath in the tunnel, so before motors were invented boats would have had to be ‘poled' or ‘legged' through the tunnel, with people stretched out on boards on either side of the boat using their feet to guide it through. The upside of course is that we're left with a fantastic heritage structure.”
To find out more about the history of the canals, visit .