West Yorkshire Fire and Rescue Service has spent more than £18,000 paying private investigators to spy on six of its staff in recent years.

Last month the Telegraph & Argus revealed that Anthea Orchard, 35, of Denholme, a former 999 call handler, had left with a £11,000 payoff after discovering she had been spied on while on sick leave.

She was signed off work with stress and hyperthyroidism, and later discovered her bosses had hired private investigators to watch her, believing she was running a balloon business while off sick.

She discovered a GPS tracker attached to her car.

After requesting answers under the Freedom of Information Act, the T&A has also discovered that Mrs Orchard was not the only worker at the fire service put under surveillance.

Between April 2008 and April 2013, six members of staff were placed under surveillance. In that time £18,366 was paid to private investigators.

In providing the information, the fire service pointed out that these costs were listed on their website as being paid to Ridings Research.

Since September 2010 there have been eight payments of this sort, with the highest being £4,096 in January 2012.

In 2010, £2,641 was paid for investigators, £6,993 in 2011 and £8,732 in 2012.

Mrs Orchard said: “There had to be a lot of surveillance carried out for that kind of money. It is a lot when they are shutting fire stations and making other cuts.

“I feel a bit sick hearing these figures. It is one thing knowing it happened, it’s another hearing how much they spent.”

When asked how many complaints they had received from staff over surveillance, the service said: “There were no complaints formally logged through our normal complaints procedure.”

David Williams, of the West Yorkshire branch of the Fire Brigades’ Union, said: “Occasionally staff might cross the line and need disciplining, but I can’t believe it happens this often.

“The fire service should be pillars of the community who can be trusted. I’m devastated by the amount of times this has happened.

“There are cuts and stations being closed, and the service are spending almost £20,000 watching employees on their days off?”

WYFRS said in a statement: “As an employer 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 proper reasons.”

e-mail: chris.young@telegraphandargus.co.uk