Workers at the site, who are repairing ancient stone walls in the precincts, alerted the cathedral's archaeologist to the find, which was discovered in the same wall as a medieval fireplace.

Archaeologist Dr Jackie Hall analysed the pieces, and discovered they were 11th century grave markings which are believed to have come from a monks' cemetery.

Dr Hall said: "It was an incredible find, and very exciting to see such a large collection of grave markers in one small area.

"They are particularly important because we don't have anything else like this in Peterborough.

"There are other grave markers of a similar date in the cathedral, but they are ornate and not visible to the public.

"Although these pieces are not as high class or as special, they are still an extraordinary find."

The markings could have belonged to monks, but are more likely to have belonged townsfolk who wanted to be commemorated at the abbey.

Although some were not immediately recognised as they have been damaged, some can be seen with crosses on them and others are slightly more ornate with gridded markers.

The work, part of a major 10-year maintenance project to restore the cathedral, was taking place between the Prior Gate and the cathedral office when the small markers were found.

Peterborough City Council archaeologist Ben Robinson said there is a lot of spectacular heritage and history and extremely interesting and important remains in the precincts.

He said: "The cathedral precincts are a treasure house of history. And as you continue beyond the cathedral and into the town there is a seamless area of heritage.

"The grave markers are incredibly rare. All of our parish churches in Peterborough date back to medieval times, but you won't find anything like this, as they have been reused over and over again.

 

"Occasionally you may find tombs of the rich and the wealthy inside the church with nice monuments, but to find the grave markers of the ordinary folk is remarkable.

"It gives us a glimpse of how these early cemeteries looked."

Once the markers have been cleaned up, they will be put in a temporary display in the cathedral.