A new book is set to cement Bury St Edmunds’ reputation as a Magna Carta town, with a leading historian confirming the crucial role that it played.

A “lifetime” of research led David Carpenter, professor of medieval history of King’s College, London, to new evidence that “proves” a meeting of rebel barons at the Abbey in 1214 did happen.

He has also managed to unveil evidence that the meeting was held a month earlier than previously thought.

The book, entitled Magna Carta and published by Penguin Classics, is set to become a standard text for students studying the famous charter, with 2015 marking its 800th year anniversary.

Prof Carpenter said: “New facts have come to light which not only vindicate the idea of a large meeting of barons in Bury in 1214, but also that the meeting happened a month earlier than previously thought.

“The new evidence proves not only that it did, but also that it took place on October 15, and not November 20. Upon learning of the meeting on his return from a campaign in France, King John made a dramatic dash to Bury on November 4, in an attempt to reassert his authority over the town. At the meeting, the barons had sworn to impose their programme on him, if necessary by force.

“Less than a month later, he granted Freedom of Election to the Church, which was a major concession, prompted by his alarm. This was the crucial decision which, the following year, led to Magna Carta.

“This chronology would indicate the Bury meeting played a much more crucial role in the build up to the revolt, which led to the eventual sealing of the Magna Carta.”

Prof Carpenter will be visiting Moyse’s Hall Museum on January 17, where he will sign copies of his new work, as well as giving a talk on the new evidence in the evening.

Lance Alexander, St Edmundsbury Borough Council’s heritage operations manager, said: “We are delighted to welcome such an eminent historian to the town and its museum.

“His ground-breaking work is based upon a lifetime’s research into the Magna Carta and he has now provided us with a compelling new argument and important new text, which are both hugely significant and exciting for the town.”

Prof Carpenter will visit Moyse’s Hall Museum between 2pm to 4pm on January 17. The book is priced at £10.99.

There are 45 places for his evening talk at the museum from 6.30pm to 8pm. Tickets cost £3 per head, and include refreshments. To book visit www.whatsonwestsuffolk.co.uk