Union leaders have demanded a meeting with West Yorkshire fire chiefs to get reassurances “covert surveillance” of its employees does not overstep the mark.

West Yorkshire Fire & Rescue has been embroiled in controversy since it was revealed private investigators fitted a tracking device to the car of one of its 999 call handlers, Anthea Orchard.

The spying operation was ordered on the mum-of-two, of Denholme Gate, after her bosses suspected she was running a balloon-making business while she was signed off sick with stress and hyperthyroidism.

The fire service has issued a statement saying it had acted within the law.

But David Williams, of the West Yorkshire Fire Brigades Union, said: “Even if it is legal, morally it is not right that this woman has had her home and her young family looked at.

“If it is legally fine, morally it is overstepping the mark. We will be writing to the Chief Fire Officer and the chairman of the fire authority to hopefully have talks so we can get more information about this case.

“It has all been very clandestine – we don’t know how much this type of activity costs. We will be asking for some sort of re-assurance they won’t go to this level of surveillance again.”

Mrs Orchard, 35, who lives with her husband, Gareth, and five-year old daughter, Ashleigh, and son Haydn, two, was exonerated by the investigation.

After negotiations with the service, Mrs Orchard signed a ‘compromise agreement’ and left with an £11,000 pay-off, in which she agreed not to take the service to court over “unnecessary surveillance or invasion into privacy and family life”.

In its statement, West Yorkshire Fire & Rescue said: “As an employer, in common with many other public and private sector employers, we have to deal with circumstances which can arise where there are reasonable grounds to suspect an employee may be in breach of their contract of employment by working in a secondary job without permission and/or by claiming benefits, such as sick pay, to which they may not be entitled.

“In exceptional circumstances, in order to establish the full facts and determine whether disciplinary action is required, it may be necessary to conduct covert observations of an employee, which is a common, long established, lawful practice sanctioned by the courts as appropriate when carried out for the proper reasons.

“Contrary to popular perception, the Regulation of Investigatory Powers Act does not apply to such activities, as both the courts and Home Office guidance make clear. We do not, for operational reasons, comment on particular methods used or the circumstances of particular cases.”