The lifespan of a Gwynedd slate quarry that was famously used to hide priceless works of art during the Second World War has been extended.

Planners agreed to a variation of conditions in plans allowing operations to continue at the Manod Quarry site in Llan Ffestiniog until 2048.

A planning application lodged with Cyngor Gwynedd said there was “sufficient reserves of slate remaining in the quarry to maintain production” until that date.

The quarry, now known as Cwt y Bugail Quarry, is operated by Breedon Group subsidiary Welsh Slate.

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Applicant Shaun Denny told the Cyngor Gwynedd planning committee on Monday, (June 24) there was still a “strong demand” for Welsh slate tiles.

He said accepting the application would “allow the quarry to increase expenditure”, thus “increasing the number of slates that could be sold” and helping to provide more “skilled jobs for the area”.

He said it would also help the nationally important cultural and heritage site by protecting its “history and place in the community” and allow time to record the remains of the gallery used as a storage facility for art during the Second World War.

Planning committee members expressed their support for the traditional Welsh industry and followed officers’ recommendations to approve the application with conditions.

Planning documents described how in 1940 the government had built “a specialist and secret storage facility” in the tunnels and caverns below Manod.

It was used to keep safe works of art which came predominantly from The National Gallery in London.

 

Cyngor Gwynedd planning document image of the storage facility at Manod Quarry from rhe Second World War

Cyngor Gwynedd planning document image of the storage facility at Manod Quarry from rhe Second World War

The vast cavern system created by the slate quarrying industry provided strong protection against aerial attack.

 

Manod was chosen due to its proximity to the railway, and it was also remote, only accessed by a winding mountain road.

Underground works had made the mine suitable for storage with brick built humidity controlled chambers and a narrow gauge rail track to move the artwork around.

By the summer of 1941 the National Gallery collection was safely stored in the subterranean facility and remained there for four years, a planning report stated.

According to the Cotswold Archaeology report, “paintings began to arrive from August 12, 1941, with completion of the transportation of 2,200 pictures by September, 1941.”

Documents also noted how the success of the Manod repository was also shown in the requests from the private collectors and institutions to store their objects of art.

It noted that it was also used by the Royal Family for safe storage of the royal collection, with drawings by Leonardo, Holbein, Claude and Michelangelo all sent to Manod.

The planning reports also described how during the Cold War, the Ministry of Works retained a lease on Manod Quarry and continued to “update and maintain the existing below-ground landscape”.

Underground work continued “on a limited scale” in parts of the mine not controlled by the Ministry of Works until around 1965.

Working of the site also resumed in 1982 with the reopening of Graig Ddu Quarry and reports stated that in 1983, the Ministry of Works relinquished its use of the former storage facility.

Whilst there has been continued quarrying around the site, the storage facility was retained.

However planning documents noted “the stability of the Manod Quarry workings had deteriorated considerably over the past 20 years”.

It added: “Today, the wartime storage facility is in a deteriorating condition predominantly due to the lack of ventilation and the instability of the quarry roof which has resulted in major rock falls.”

Experts still considered its presence to be of “high heritage value”, however.