Their show of hands for the firm came as they discussed retrospective planning permission for the erection of fans on a gantry next to a new cooling tunnel extension forming part of the production line at Woodside Road.

The application was lodged after council officials considered a change in the siting of the fans from their original location to be a “material alteration” from what had been approved originally.

Councillors learned that when permission for the cooling tunnel was first granted in September, 2002, there were no conditions limiting the use of the fans.

But, when the issue went back before the committee, planning boss Alex Anderson recommended restricting the hours of operation of the equipment on the gantry to between 5.30 am and 8 pm, Monday-Saturday.

He also put forward a recommendation that the fans only operate on 10 Sundays each year.

The restrictions stunned the firm, which celebrates its centenary this year and has been able to operate without any limits on its hours.

Director Joseph Mitchell addressed the committee and said that, had the firm known such a condition on operating hours would be put forward, it was doubtful that it would have invested the £1.25 million on the air tunnel.

“This limit on operating hours will have a detrimental effect on the business,” he warned. “You cannot switch one machine off in isolation without bringing the entire factory to a stop.

“Therefore this proposed working hours limit not only affects the gantry equipment, but the entire factory.”

He said it was vital to the business that no unnecessary constraints which reduced its flexibility are “forced upon us”.

“We may never need to work outwith the proposed restriction but, having invested a substantial sum of money, we would like the ability to do so if required and hence maximise our investment,” Mr Mitchell continued.

He pointed to an assessment which stated the change in the siting of the fans and the increased gantry height had a knock-on in terms of noise of less than one decibel.

The council’s own environmental and consumer protection staff said this level was “imperceptible to the human ear”.

Despite the assurance, Councillor Dick Speirs said it was clear local people were becoming increasingly frustrated and angry at the continuing expansion of the factory.

He described the operating hours on offer as “extremely generous” and added if Mr Mitchell was still unhappy with the restrictions “he should seriously start looking for an alternative site for his factory”.

Councillor Ruth Leslie Melville rounded on her colleague for “glibly” suggesting the firm looks for other premises, describing him as “downright negative”.

She feared a serious loss to the economy if the company relocated outside Angus.

“I think we have to be very careful here,” Mrs Leslie Melville continued. “We have an extremely efficient and well-run business, a successful business.

“I fear if we start putting a lot of restrictions on them, we are going to hinder their progress, their ability to employ people, their efficiency and that is going to be detrimental to their business.”

Councillor Bob Spink said it was “quite inappropriate” to encourage a business to spend money and then restrict its working for the first time.

“They are looking ahead and at expanding their business for the good of Angus,” he continued. “For Councillor Speirs to suggest they go elsewhere is nonsense.

“I certainly feel that we are penalising this company very unwisely if we put on these conditions.”

On the conflict between Mitchell of Letham and its neighbours, he added that people living in close proximity to the factory made a conscious decision to move there.

Committee convener Councillor Stewart McGlynn said if there are problems with noise in the future, there are other places such as the council’s environmental health and consumer protection department people could go to.

Committee members voted to grant retrospective permission and defeated a move by Councillor Helen Oswald to defer the application to allow Letham Community Council to be consulted.