Recycling might be all the rage in the 21st century, but finds in Caister suggest the Ancient Romans had gone green thousands of years before us.

Archaeologists studying glass fragments unearthed at Caister say they have found evidence that the Romans were recycling glass 1,500 years ago – way before councils were providing green bins.

According to a study co-authored by Harriet Foster, from Norfolk Museums and Archaeology Service, large quantities of glass were recycled in Britain during the 3rd and 4th centuries AD.

Fragments of glass from excavations at the Roman fort at Caister were among glass which was examined in the study, along with other glass from the Norfolk Museums collection.

During excavations in the 1950s, fragments of glass vessels were recovered at the shore fort that suggested its inhabitants had access to a large range of glass wares, most of which may have been made locally but with at least some being imported over considerable distances.

Ms Foster, who is based at The Shirehall in Norwich, and Caroline Jackson, from the archaeology department of Sheffield University, analysed the chemical composition of 128 samples of glass from 19 sites across Britain, including Caister.

Ms Foster said: “We used a technique that meant having to destroy the glass in question, so we had to make sure the information we were getting about each piece outweighed the fact that we’d be destroying a tiny piece of valuable archaeology.”

The Romans used to decolour glass using the metals antimony and manganese, and more than half of the samples analysed were found to contain both those elements.

The conclusion of the researchers is that the presence of both elements shows the Romans were recycling, with skilled craftsmen mixing pieces of broken glass, which had already been decoloured, to create new glass.

However, the researchers behind the study, published in the Journal of Archaeological Science, suspect that it had little, if anything, to do with the first shoots of environmental awareness.

It was probably more because glass became scarcer in the northern fringes of the Roman Empire, such as Britain, during the last century of their rule.

Ms Foster said: “We think this means the Romans were increasingly relying on recycling to produce the vessels they wanted, possibly because less glass was coming into that part of the Empire by that time.”