The last time my family and I visited York, we wandered outside York Minster but our indigenous frugality (being ourselves of Yorkshire soil) baulked at the then-recently introduced admission fee of £10 to go inside. If you too visit York and find yourself in similar frugal mode, let me advise you to take a hold of yourself, with an optional shake, and remind yourself never to put filthy lucre ahead of artistic splendour. For York Minster, as well as in itself being one of the great gothic cathedrals of northern Europe, and thus replete with the resplendent architectural beauty for which such cathedrals are known, contains also the largest expanse of medieval stained glass in the world, including the subject of today’s blog, the Great East Window.

Some call it England’s Sistine Chapel, and indeed, had it been done in paint, instead of in glass, it might well be considered a rival to Michelangelo’s masterpiece in Rome. However, stained glass has always fallen on the wrong side of that dividing line between fine and applied art, and thus it is seen primarily as a craft. Let’s not fall for that one. The great east window in York Minster is one of the triumphant achievements of the Middle Ages: 1,690sqft of artfully executed stained glass, recounting the story of the world from Creation to Apocalypse.

It was in 1405 that John Thornton of Coventry was commissioned to glaze the east end of the Lady Chapel. A copy of Thornton’s contract for the window survives, specifying that he was to draw all the cartoons, and paint a large number of the individual panels. For all this Thornton was paid a total of £56, and contracted to complete the job inside three years. For doing so, Thornton received a £10 bonus, and proudly put the date of completion – 1408 – at the very apex of the window.

Doubtless Thornton had behind him a team of glaziers, hired locally or brought with him from Coventry, but the painting on the glass would primarily have been his. It was Thornton’s task too to turn the commissioner’s highly theological and precise concept into a work of art. And this he self-evidently did.

While much medieval glass is dominated by reds and blues, John Thornton had a penchant for yellow as his base colour. In addition, the painting in Thornton’s faces had greater realism (and meticulously drawn hair) than his rivals. The typical Thornton face is sensitive, with eyes down-turned, a small mouth and a somewhat prominent nose. What Thornton was pioneering in his glasswork was the European style – new to England – known as International Gothic. It is elegantly stylised work; for sure, the York commissioners were buying cutting edge art, and, of course, good glass can’t be made without a cutting edge.