A window on York Minster’s history

NICK Teed leans in close to study the detail in one of the magnificent stained glass panels that make up York Minster's Great East Window.

The image he shows me on the 600-year-old glass is not one for the faint-hearted.

"This is the mouth of Hell," Nick says, indicating a gaping, red-lipped mouth.

"You can see the jaws here, and these great teeth or fangs, coming up. And these" - he gestures at a horde of screaming sinners apparently in the act of being swallowed - "these are people being snatched into the mouth of Hell."

It is an image potent enough to give you nightmares, even after all these centuries.

The skill of the medieval artist who painted this window - glass painter John Thornton - was such that you can see the horror on the faces of those damned people still, frozen there for all eternity.

It is not surprising that the images are so graphic.

Much of the Great East Windows is taken up with the story of the Apocalypse - the great battle between God and Satan that ends with Armageddon, Judgement Day and the ultimate triumph of good over evil.

The panel includes scenes such as the Dragon And The Beast being worshipped, The Four Horsemen Of The Apocalypse, Satan Bound and The Judgement Of The Lost.

Seeing the glass at close quarters is a real eye-opener.

To reach here, Nick and I have climbed up a narrow spiral staircase in the Minster's South East Tower, and have made our way along a narrow, stone-walled balcony that runs beneath the window high above the Lady Chapel.

It is easy, from up here, to appreciate the superb craftsmanship and artistry that went into the window's making.

Nick singles out a panel at the very bottom of the window.

It depicts King William I, King Edward the Confessor and King Edward III.

It is the exquisite detail and skill with which the three kings' faces have been drawn that makes this glass so special, Nick says.

"It is a fabulous example of John Thornton's painting."

Not that many people, looking up at the windows from the floor of the Minster - or, before the scaffolding which obscures the cathedral's East Front went up, from College Street outside - would have realised that.

The window was created between 1405 and 1408 and, at approximately the size of a tennis court, is thought to be the single largest expanse of medieval glass in the world.

But over the centuries, its 144 panels - and the 167 smaller "tracery lights" that form the arched section at the top - have suffered the ravages of time and the weather.

They have been cracked, broken, damaged by the elements and repaired and restored countless times.

During the Second World War, all the glass was taken out and put in storage - and in the 1950s, under Dean Milner White, the glass was restored before being replaced.

As a result of these centuries of wear, tear and repair, some of the original glass has been lost and replaced with inserted newer glass, panels have been jumbled and mixed, and shattered fragments of glass have been pieced together with the help of heavy leading.

The result is that, while the window still blazes with colour - at least when not obscured by scaffolding - much of the story the original window told has been obscured.

It is Nick's job, as conservation manager at the York Glazier's Trust, to lead the team which will restore the window to its full glory.

The scaffolding which obscures the whole of the Minster's East Front has been put up in preparation for a major £23 million restoration project that is expected to take many years.

Minster bosses have just lodged a bid for more than £10 million of heritage lottery cash to help fund the project.

The window will form just a part of that overall restoration scheme - but a significant part.

Nick and his team of experts will take down and restore every one of the 144 panel and 167 tracery lights, attempting to return them to something like John Thornton's original vision.

Before that process begins, however, they have to determine the best method to use - and the best way of protecting the glass once it has been restored.

Already, four of the 144 panels have been removed, and craftsmen have spent the past 18 months experimentally restoring them, trying to decide upon the best approach.

Down in the Glazier's Tust workshop, Nick shows me the end result.

It is the final panel in the window's Apocalypse sequence, showing St John sitting at the feet of a haloed God. God holds a book with the words "Ego sum alpha and omega" - I am the beginning and the end.

It represents the triumph of God over Satan - with St John himself beginning to write down in Latin the Book of revelation.

Nick shows me a photograph of the panel before it was restored.

It is dark and grimy, the glorious colours heavily laced with lead tracery where broken fragments of glass have been fixed together by previous restorers.

The restored panel, by contrast, glows with colour. Much of the heavy leading has been removed, and replaced by resin bonding - and what lead remains follows the contours of the panel's design.

It is a glorious work of art restored by master craftsmen. Just what the magnificent Great East Window will look like once it has been fully restored with such care and dedication, and once the scaffolding has finally come down, only time will tell.

But it will certainly be a sight worth seeing.

The story of the Great East Window

The 167 tracery lights that make up the top of the window show scenes representing the "celestial hierarchy": God with the angels, the nine orders of angels; the sons of Jacob, Moses and Aaron.

Below that, the first section panels depicts scenes from the Old Testament, such as the Creation, Cain killing Abel, the death of Sampson, the story of David and Goliath.

Then comes the main section of the Window, telling the story of the Apocalypse. The often graphic panels include the horsemen of the Apocalypse, the legions of Hell, mountains cast into the sea, the locusts, the sun darkened, the Beast making war, the fall of Babylon, the army of heaven, Satan bound and the Judgement of the Blessed and Judgement of the Lost.

Restoring the glass

It could be as much as two years before work starts in earnest on restoring the bulk of the Great East Window's stained glass.

Before then, craftsmen have first to decide what approach to use, and how best to protect the glass once it is replaced.

Only then will the process of removing the glass begin.

The aim of the restoration, explains Nick Teed, will be to recapture as much of the vision of the window's original designer, John Thornton, as possible.

That, however, poses a real challenge, because how does anybody know what the original window looked like?

In some panels, as little as 25 per cent of the original medieval stained glass remains. The remainder is bland, coloured glass that has been used by previous restorers to fill in gaps, or else medieval stained glass taken from other windows and used to repair the Great East Window.

There are ways, however, for Glazier's Trust craftsmen, working closely with art historians and stained glass experts, to try to piece together what the windows did look like.

There are many repeating details on the windows, for example - borders and designs that occur again and again.

By looking at the designs on undamaged sections of glass, craftsmen can recreate these in damaged areas.

Certain characters and faces also occur again and again - so, where these have been lost or damaged in certain sections of window, craftsmen can recreate them.

They can also study photos taken in the 1940s, before the last restoration, and medieval art contemporary with the creation of the window.

Still, Nick says, there is a danger of restorers going too far and applying too much guesswork and conjecture.

The Glazier's Trust craftsmen have decided to adopt a fairly cautious approach, restoring what they know from the evidence would have been there, and elsewhere contenting themselves with removing unsightly leading from previous restorations and replacing it with finer lead work and resin bonding.

Where craftsmen do use new glass to repair damaged panels, they will use methods as close to those adopted by the craftsmen of 600 years ago as they can.

Hand-produced blown glass only will be used, coloured using the same methods as the medieval craftsmen - blue glass, for example, will be produced by mixing cobalt with the molten glass. The painting techniques and materials will also be the same as those used by John Thornton.

Protecting the glass

Over the next year, says Glazier's Trust director Peter Johnston, craftsmen will also be looking at the best way of protecting the restored glass from the elements.

Protective glass to cover the medieval stained glass has been used since the 1860s. At the moment, there is a layer of diamond-patterned leaded glass, set a few centimetres in front of the medieval glass, to protect it from the weather.

There are concerns, however, that condensation may form between the two layers of glass - and also that the leading on the protective glass spoils the design of the magnificent windows when seen from outside.

Over the next year, the trust will be trialling a number of different types and styles of protective glass on a smaller window next to the Great East Window, to see which is best at reducing condensation and dust.