A STAINED glass window the size of a tennis court which has been hailed the largest and most important piece of medieval glass in the world cost just £56 to install.

But 600 years on, York Minster's Great East Window is about to undergo a major £6million renovation.

The work is part of a bigger project to restore the east front, and is thought to be the most important of its kind in Europe today.

About £30million is needed for the venture, according to Dr Richard Shephard, director of development for York Minster.

"The project has been called in by the Cathedrals Fabric Commission for England because it is probably the most important project in Europe at the moment," he said.

"There's enormous national and international interest in what we are doing.

"Until that body, and English Heritage and the Society for the Preservation of Ancient Buildings, have come to a consensus of opinion we can't start doing the stonework." Experts have taken 11 pinnacles of glass out to assess the repair costs while the surrounding, weathered stonework also has to be replaced.

"It has fallen to our generation to undertake this major piece of restoration," said Dr Shephard who said the entire great east window would have to be removed.

In 1405, John Thornton, from Coventry, was commissioned to undertake the window project, providing workmen and materials. He was paid £46 with a £10 bonus upon completion in 1408.

"Nowadays it will cost £6million to repair the glass," said Dr Shephard.

The 10-year east front project is expected to cost £3million a year.

"This project is absolutely vast," he added.

Harrogate and Knaresborough MP Phil Willis who took a tour of the east front said: "It was remarkable to see stonework from the 14th century and glass work which was crafted 600 years ago.

"Not only will this project restore one of our most important buildings but if sufficient funds are raised it will provide more opportunities for apprentice craftsmen."

York Minster receives no money from central or local government, and must raise the millions needed to restore the east front from charitable donations.

To support the restoration work send a cheque, payable to York Minster Fund, to the Development Office, Church House, Ogleforth, York, YO1 7JN.

Updated: 10:51 Monday, October 03, 2005