Housebuilder Persimmon Homes has been fined for failing to protect medieval timbers during the conversion of a 16th century grade II*-listed property in Stalybridge.

The company converted Stanley Hall in Millbrook into townhouses and apartments in 2009 after the building had lain derelict for a number of years.

But during the works part of the building’s ancient timber core was destroyed, even though it was rated as of “immense historical significance” by English Heritage and its loss was “easily avoidable”.

Tameside Council brought a prosecution against Persimmon which pleaded guilty to breaching listed building condition and to damaging a listed building.

Tameside Magistrates’ Court fined the company £10,000 for the first offence, £500 for the second, and a £120 victim surcharge was imposed

The court also awarded the council £5,900 in respect of the costs of investigating and prosecuting the case.

In determining sentence, the court took into account the fact that the building had been restored by Persimmon at significant cost and that the company had entered early guilty pleas.

Councillor Peter Robinson, executive member for land-use at Tameside Council, said: “The fine is not intended to reflect the value of the lost 16th century timbers as they were irreplaceable.

“It is to punish the firm for its actions and omissions. It shows that Tameside Council will not hesitate to take action against owners and developers of listed buildings whenever it may be necessary.

“We are happy with the sentence as there was no evidence that Persimmon achieved any significant financial gain by what it allowed to happen.”

Persimmon Homes North West managing director Neil Follows said: “Prior to commencing the restoration works, no more than the front façade of the building remained. In fact the building was on English Heritage Buildings at Risk Register for decades. The restoration costs totalled £5.5m and took several years to complete.

“Unfortunately, during the course of the restoration, a section of the timber frame was stolen from the site. The incident was reported to the police who investigated the theft. The loss of some of the timbers ensured that they could not be used in accordance with the approved plans.

“Persimmon Homes deeply regrets the incident as the company was keenly aware of the importance of the original timbers, many of which have been reused within the hall’s restoration.

“The remaining pieces of the historic timber frame are now in safe storage and the company is in discussions with the local museum service regarding a new public display.”