Stained glass windows overlooking the tomb of Edward, Prince of Wales, were destroyed by Puritan iconoclasts in the 1640s, allowing damaging UV rays to enter the cathedral unfiltered. Since then, clear replacements have been installed and the deterioration of the paintwork on the 14th century canopy surrounding the prince's resting place has continued.

The brilliant colours of the artworks that look down on the bronze figure of the prince are fading rapidly and the red pigment used by the original artists is turning black.

In a bid to halt the centuries of damage, restoration experts have now installed a huge blind to shield the artworks from harmful rays and created a system for regulating the humidity.