A textiles firm will replace 49 UPVC windows in a listed Edwardian mill which were installed without planning permission.

Ruia Group, who run Kearsley Mill in Prestolee, have published retrospective plans after they changed the windows at the heritage building without consent after a storm, during which falling glass and window frames wrote off a car and narrowly missed a person.

The five-storey, Grade II-listed late period cotton spinning mill is described as ‘a rare example of an Edwardian textile mill that is still being operated in its original use’. The retrospective planning application, submitted in the past week, describes the events leading up to the windows going in.

A planning statement said: “During a storm in April 2017, a strong easterly wind blew out a window on the west side of the building on the fourth floor.

“The wind rushing through the hole where the window was began to create a build-up in air pressure and blew two more windows out on the south side of the building.

“These overlook the staff car park and two cars were damaged, one written off, and a staff member who was crossing the car park at the time had a near miss with one of the falling windows. “Given the seriousness of the incident and the potential for loss of life if any more windows were to blow out, we took the decision to install new windows as soon as possible.

“It is our understanding that the previous maintenance manager did not realise that the windows were included as the original fabric of the building and therefore did not stop at just replacing the three windows that blew out but replaced a further 46 windows that were badly deteriorating and had the potential to harm or kill someone.”

Ruia Group say they now understand that the works are unauthorised and represent harm to the designated heritage asset. They are now seeking permission to install like-for-like timber windows to protect the building’s listed status.

Also included in the plans are other changes to the building which have been undertaken since the mill was listed as a heritage asset. Among the changes sought to be regularised by the application are removal of original glass panes of some windows, the erection of internal showrooms, the addition of modern ventilation to the main former spinning rooms and the installation of three electric vehicle charging points.

The report said the company had been working with Bolton Council’s conservation officer the possibility for a phased replacement of the unconsented UPVC windows was discussed. The report, said: “It was suggested that given the number of windows, this may be agreeable.”

Planners at Bolton Council will consider the application in the coming weeks.