The scale of dry rot in Norwich's historic Shirehall is worse than initially thought, worried museum bosses have revealed.

The issue in the Grade II listed building, which was the city's court for more than 180 years, was first identified in 2019.

At that time, it was thought to affect a relatively small area of the wood panelled Victorian courtroom, which was restored in 2013 after ceasing use as a court in 1988.

But studies revealed it was a "significant" outbreak which covered about 25pc of the space in the Market Avenue courtroom.

Stuart Garner, Norwich Museums operations manager, said: "Most alarmingly, and most recently, we discovered it is in within the structural timbers of the roof as well."

Large sections of the courtroom have been stripped back to expose the timbers beneath and allow the building to dry.

The leaking roof, which caused the conditions for the dry rot - a fungus called Serpula lacrymans - to thrive, has been fixed.

But the museum service needs to get planning permission to take the necessary action to stop the fungus eating the timber.

That will include a specialist contractor removing affected timbers, replacing them and putting in steel barriers to stop the dry rot spreading.

Mr Garner said: "It is a significant piece of work which will take the courtroom out of action for the next six to 12 months.

"Unfortunately for us, the courtroom is nearly all made, apart from the external brickwork shell, of timber.

"In order to be able to safeguard it, the interventions include needing to place a steel barrier between brickwork and timber throughout the courtroom, in order to create a physical barrier to stop that dry rot's spread, should we have future water ingress issues."

The courtroom has, in recent years, been used for 'living history' performances, as well as for public and private events.

Norfolk County Council's Conservative-controlled cabinet previously agreed to make £580,000 available to tackle the dry rot problem.

Council bosses said it was hoped that sum would help cover the next phase of work, which is now out to tender.