Fragments of a priory’s medieval tiled floor that spent almost 60 years stashed in a toffee tin after being pocketed by a nine-year-old boy during a family outing have finally been handed back.

The three pieces of decorative clay tiles, dating from the late 13th to early 14th century, were taken as a souvenir by Simon White during a family visit to Wenlock Priory in Shropshire in the late 1960s.

White, now a 68-year-old retired chartered surveyor, found the fragments in an old toffee tin during a house move and owned up to English Heritage. He told officials he recalled his father encouraging him to take the pieces but had always felt a little uneasy and was delighted when he rediscovered them.

“I can remember the day this all happened with my father standing guard,” he said. “Heaven knows what he would have said if we’d been caught. What happened to the tiles afterwards I’m not really sure, but they survived numerous house moves and assorted family upheavals only to turn up in my loft earlier this year in a battered tin.”

With the help of family diaries, White worked out that they probably came from Wenlock Priory and contacted the site’s custodians, English Heritage.

Matty Cambridge, assistant curator at the charity, said medievalists had concluded White was right to pinpoint Wenlock as the scene of the act. She said tiles like the ones White had taken were only known to have existed at three places in Shropshire: Haughmond Abbey, Bridgnorth Friary and Wenlock Priory.

Cambridge added: “Given Bridgnorth Friary has no in situ tile and wasn’t excavated until after Simon’s trip, and Haughmond Abbey only has a small patch of tile still at the site, we can narrow down the tiles found to Wenlock Priory.”

Wenlock was once home to Cluniac monks, who were fond of elaborate architectural decoration. Cambridge said English Heritage was particularly thrilled that one of the fragments had a dragon motif on it, which was previously unknown at the site. “That’s quite exciting,” she said. Another fragment shows the face of what is thought to be a lion, or possibly a grimacing face.

White met Cambridge at Wenlock Priory to hand the fragments back. “He wanted to make a bit of a pilgrimage,” Cambridge said. “There are no hard feelings. He was only nine and was told: ‘Oh, this is pretty – take it home.’ We are very grateful to Mr White for coming forward.

“It’s not unheard of for mementos to have been taken from historic buildings, though is it unusual in this case that the artefacts were kept so well for so long and preserved. Nowadays we have far more stringent measures in place to prevent it, but if Mr White’s example pricks anyone else’s conscience from years ago, we’d love to hear from them.”

The tiles will not be put back on to the floor but will be moved to an English Heritage archaeology store for further analysis.

White said since his retirement he had taken a keen interest in archaeology. “The local society I’ve joined are likely to take a dim view of this. It’s only right and proper that the tiles are returned home.”