Archaeologists have finally been able to put a date to a piece of stained glass from one of North Yorkshire’s most famous ruins.

Rievaulx Abbey, near Helmsley, has been the site of historical detective work since fragments of its stained-glass windows were recovered from rubble there in the 1920s.

Some of the original archives papers from these excavations have now emerged, including colour depictions of a small number of the glass fragments.

Recently, while flicking through the folios and holding a random piece of glass, Susan Harrison, an English Heritage curator, found the picture on the page and the one in her hand were the same, meaning the glass could be dated to between 1275 and 1300 – earlier than believed.

She said: “The glass we have identified came from the Chapter House – the Abbey’s ‘Board Room’ – where key decisions were made.

“It’s exciting being able to add a little story to an ancient piece of glass and we have now matched other fragments with the old paintings.”

Some of the historic glass has now been returned to Rievaulx and put on display in the site’s museum, along with copies of the 1920s paintings and other finds.