Stained glass windows in Canterbury Cathedral overlooking the 14th century tomb of Edward, the Black Prince, were destroyed by Cromwell’s puritan hordes in the 1640’s. Over the years clear glass was put in the place of the original stained glass, but that doesn’t filter damaging UV rays the way stained glass does.

The sun is damaging paintwork on the canopy surrounding the Black Prince’s effigy, so much so that conservators have installed a first-of-its-kind system of blinds and humidity control.

Leonie Seliger, the head of stained glass at the cathedral, said: “As far as we know this is the first time in the world that such preventative measures have been adopted.

“The information from the sensors is relayed onto a computer within the cathedral precincts 24 hours a day, and then the results are sent off for analysis.

“Just a few degrees of temperature change can drastically affect the humidity levels so we are constantly on watch so that light levels can be adjusted via the blinds and temperatures controlled.”

Hopefully it’s not too late. The colors are fading rapidly, and the red pigment is turning black.

Edward, Prince of Wales, son of Edward III, was known as the Black Prince because of the characteristic color of his armor, or because of an ornate cuirass he was given after the Battle of Crécy. Or else it’s a phrase of 16th century coinage and he wasn’t known as the Black Prince at all in life.

He died a year before his father, so he never did get to be the Black King.