Experts transforming part of Durham Cathedral into a world-class museum are finding surprises at every turn. Mark Tallentire was granted an exclusive behind-the-scenes tour 

TOM Billington’s last job was building the Olympic Park for London 2012.

Now he’s gone from Europe’s biggest building site to one of its most stunning treasures.

As construction co-ordinator on Durham Cathedral’s £10m Open Treasure programme, he is responsible for delivering a vision to turn part of the 900-year-old Norman shrine into a world-class exhibition venue, fit for the 21st century tourist and capable of showcasing some of civilisation’s most precious artefacts, both from the cathedral’s vast archives and across the globe.

“It’s brilliant,” Tom says.

“I’m just a builder from south London. To come here and explore 14th century monastic buildings is a pretty good job.

“I’ve got a big key and I get to just wander round the site.”

Of course, there’s a bit more to it than that.

The Monks’ Dormitory, one of England’s two such remaining medieval halls with stunning wooden beams under a dazzlingly high roof, is being turned into a paid-entry attraction that will take visitors on a journey through the cathedral’s history from its foundation by the community of St Cuthbert through the Reformation, its use as 18th century clergy houses and a lending library to the present day.

From there, a new passage will lead on to a new exhibition space benefitting from tight environmental controls, capable of hosting the most precious and delicate of treasures.

Down a level and the grand finale will be the renovated Great Kitchen, most recently a bookshop, that will house the Treasures of St Cuthbert.

After years of planning, work began on site in June and is around one-third through, with opening anticipated in early 2016.

Access to the Monks’ Dormitory is via scaffolding and a vacated stained glass window.

Huge walls have had their joints painstakingly chiselled out by hand, ready for replacement with a more sustainable lime-based mortar.

Inside, huge Roman and Saxon stones, although to large to be removed, have been carefully bagged and relocated, allowing workmen to install a lift and, in future, a welcome and information desk.

All the books are gone, the first time the monastic library has been moved out of the cloister since the cathedral was built; and are being stored carefully nearby.

A 1950s infill has been removed to make way for the new-look chamber and inside the Great Kitchen a bird cage-like tower of scaffolding supports the octagonal structure.

Norman Emery, the cathedral archaeologist, walks in, keen to discuss two new finds.

“It’s quite unique to be starting from scratch and creating a new museum, which is really what we’re doing,” Tom says.

“We want people to enjoy the architecture as well as the treasures because the buildings are just as much treasures as they are – and in some cases they’re older.”

Open Treasure has to date received pledges of around £8m, including £3.9m from the Heritage Lottery Fund.

Donations can be made directly or by buying £1 bricks in a Lego model of the cathedral currently under construction in the undercroft.

For more information, visit durhamcathedral.co.uk/open-treasure