One of Norwich's most famous buildings is far older than first thought, according to new research.

The Britons Arms on Elm Hill has been dated to before 1347 – making it around 60 years older than earlier estimates.

Historian Franziska Callaghan researched the building, which has one of the last thatched roofs in the city, for the Norwich Preservation Trust after they took over the lease, following a campaign to stop its sale last year. She found documents which referred to the Britons Arms in 1347 as Le Godes Hous.

Mrs Callaghan believes the coffee house's chimney also makes it older than the 15th century. She said: 'With influences from the Low Countries and other continental countries trading with medieval Norwich, it is highly likely that the building with its integral chimney stack dates to the 14th century.'

Her report for the trust also raises questions over the grade-two-listed building's earlier use. She believes the Britons Arms was not used as a home for religious women – called a beguinage, contradicting earlier theories.

Experts from the University of Nottingham visited the Britons Arms yesterday to attempt to date the timbers, but found the tree rings were too big to date.

Gilly Mixer, who runs the coffee house with her sister, said: 'They are going all out to find out what the age is. It would be nice to get some dating done to get a more definite idea.'