A chimney on Ipswich's beloved Christchurch Mansion is at risk of collapse – prompting the council to apply for planning permission for repairs.

Chimney seven – on the eastern side of the Grade I-listed building – has been deemed unstable following an inspection by stonemason and surveyor David Adamson earlier this year.

East Anglian Daily Times: Chimney seven (centre) is due to be repaired by Ipswich Borough CouncilChimney seven (centre) is due to be repaired by Ipswich Borough Council (Image: Archant)

A report submitted to the council said up to 80% of the pointing an bedding mortar of the internal bricks is now missing, while the chimney can be seen to be leaning out and twisting.

The twisting is said to be causing bricks on the back of the chimney to become misaligned and displaced.

In his report, Mr Adamson said he believes it "highly likely" there could be a "total collapse" of the chimney should the problem not be addressed.

The problem – affecting the top 25 courses – is understood not to extend further.

East Anglian Daily Times: The mansion was gifted to the town of Ipswich by the Cobbold familyThe mansion was gifted to the town of Ipswich by the Cobbold family (Image: Archant)

Mark Hunter, Ipswich Borough Council's operation manager for major capital schemes, insisted there is no safety risk to the public.

Mr Hunter said: “We need to repair a chimney on top of Christchurch Mansion.

"We have had it surveyed and found some pointing and bedding mortar missing.

"The chimney can be seen be seen to be leaning and twisting and if we did nothing, the chimney might, in time, collapse.

"So we are seeking planning permission to rebuild the chimney as part of our commitment to well-maintaining one of Ipswich’s best loved buildings.

“There is no public access to where the chimney is located and therefore no safety issues.”

It is expected that 500 bricks will require re-bedding, with the aim being to reuse as many of the existing bricks as possible.

The mansion is widely regarded as the jewel in Ipswich's crown, with its rich history stretching back more than 500 years.

The mansion lays on the site of the 12th century Holy Trinity Priory, which was demolished after the dissolution of the monasteries in the mid-1500s.

The mansion was built by Edmund Withypoll, whose father Paul had bought the land following its suppression.

East Anglian Daily Times: Felix Thornley Cobbold (1841-1909)Felix Thornley Cobbold (1841-1909) (Image: Dave Kindred)

Again facing an uncertain future, the mansion was bought by Felix Cobbold, who wanted to save it from demolition.

Mr Cobbold gave the mansion to the Ipswich Corporation on the condition it bought the surrounding parkland for the people of Ipswich.

The mansion is now run by Colchester and Ipswich Museums and acts as the town's second free museum, housing collections of Thomas Gainsborough and John Constable.