Historical detectives have tracked down the only surviving artefact from the Second Battle of St Albans - Britain's second oldest cannonball.

St Albans has the distinction of being the only medieval town in England where two battles in the War of the Roses were fought, the first on May 22 1455 which saw the capture of King Henry VI by the Duke of York's forces, and a rematch on February 17 1461 in which the Lancastrians defeated the Yorkist Earl of Warwick.

No artefacts survived from either battle, until now.

By the 1460s warfare had moved on with the development of artillery in the form of cannons and handguns. The Earl of Warwick was fascinated by such weapons and had them as part of his 1461 deployment to the north of the city centre around Bernards Heath, and in 2014 a metal detectorist found a cannonball in this area.

The Battlefields Trust authenticated the site of the find as being likely to be on the battlefield and Professor Glenn Foard, an archaeologist from the University of Huddersfield, authenticated it as a Wars of the Roses period cannonball. Glenn is best known for discovering the actual site of the Battle of Bosworth in 1485 and the likely location where Richard III was killed.

A subsequent owner of the cannonball kindly allowed it to be briefly exhibited in St Albans Museum in early 2016 but it then disappeared from public eye, remaining in private ownership with its whereabouts unknown for many years.

After years of searching for the artefact, Dr John Morewood, a member of the Battlefields Trust and president of St Albans and Hertfordshire Architectural and Archaeological Society (SAHAAS), recently tracked it down to The Lanes Armoury in Brighton, one of Britain’s leading antique arms and armour dealers, where it had unexpectedly gone on sale.

Dr Morewood and the Trust moved quickly to secure its purchase, and he explained: "The intention is to pass it back to St Albans Museum + Gallery so that it can be properly conserved and displayed. It will, of course, be the star exhibit in a forthcoming 2023 exhibition."

Cllr Anthony Rowlands, chair of the district council's public realm committee said: “It is wonderful that The Battlefields Trust and SAHAAS have done this vital work to track down the cannonball. This artefact is of major historic importance and will allow the museum to highlight yet another fascinating part of St Albans’ history.”

Museums manager Farhana Begum added: “As a museum we know the power a single object has in bringing a story to life and so we’re very grateful to members of the two organisations for their efforts to bring this cannonball back to St Albans. We look forward to working with SAHAAS on a future exhibition which will showcase this and many other wonderful objects.”

SAHAAS vice president Dr Peter Burley, organiser of the proposed 2023 exhibition, confirmed that the cannonball is the only relic of any sort that can be authenticated to the 1461 battle and is a unique piece of battlefield archaeology.

He said it is actually the second cannonball to be found from the battle in the same area of St Albans. The first was found in about 1530 by a pupil playing truant from St Albans School who later became mayor and recorded the incident in his memoirs. This first cannonball has sadly long since been lost.

The cannonball’s diameter is 47.1mm, it weighs 640 grams and it is made of lead. It is in a good state of preservation and is very similar to cannonballs found in Barnet from the 1471 Wars of the Roses battle which are now conserved and displayed in Barnet Museum.