Economic historians at Queen Mary University of London found the early accounting document among the pages of a bound collection of traditional English crests held at the London College of Arms, the headquarters of British heraldry.
The document is a list of debtors and creditors for Florentine merchant banking company Domenicio Villani & Partners, a university release reported Monday.
The banking record is only half-covered by the coats of arms painted in 1480, as good quality paper was rare at the time and any sheets of sufficient quality that were available were re-used, researchers said.
The discovery was made by researchers involved in the decade-long Borromei Bank Research Project, documenting the activity of Italian merchant bankers operating from London in the late medieval period.
"What makes the discovery of these pages so surprising is that, usually, the foreign offices of the Florentine companies periodically sent the books back home so they could be checked," historian Francesco Guidi-Bruscolo said. "In this case, the books remained in London, where they gradually lost their documentary value and some 55 years later were considered scraps of good quality paper to be re-used for the drawing of coats of arms.
"It is not possible to reconstruct, from such a limited number of transactions, the full activities of the company to which the ledger belongs, but we can get an idea of the goods being traded in the London marketplace," Guidi-Bruscolo said. "Raw wool, woolen cloth and tin were popular exports, while we imported spices, dyes and other luxury goods."