The problem is costing businesses, the economy and taxpayers millions of pounds.

It was for this reason that Kineton resident and former Warwickshire police officer David Kearns set up the investigation company Expert Investigations.

Readers may have seen Mr Kearns in a BBC2 documentary called Who's Watching You? Reporter Sundari Sankar spoke to him to find out the truth about his job.

It is a sign of the cash-strapped times that the services of Expert Investigations are increasingly in demand.

The Coventry-based agency carries out undercover surveillance using hidden cameras and listening devices to catch thieves red-handed at workplaces across the UK.

And not much gets past a company that boasts more than 400 years of combined police detective experience. Former military officers from the Special Air Service and the Royal Marines add to the mix in the 40-strong team.

Mr Kearns said incidents of false absenteeism and employees stealing from the workplace have become more common since the recession took hold, and are keeping the detective agency busy.

Financial worries have apparently pushed more people to acting dishonestly in the workplace.

Mr Kearns said: "That includes not just blue-collar workers, but senior staff, managers and directors as well. The perception is that it's a victimless crime."

And in another dimension to the problem he has discovered people who are off work long-term sick have used the money earned in sick pay to set up another business.

Investigations in the workplace are usually complete within five day and surveillance can begin immediately.

Mr Kearns said: "It's very rare that our operations are not successful because the clients generally know what's going on, but they need to gather evidence.

"It's up to the client whether they want to involve the police or deal with the problem internally."

Expert Investigations offers a worldwide service for all areas of its work and investigations cost anything up to £600,000.

Their areas of expertise also include overt close protection – the firm was recently employed by an A-list celebrity to provide security for her wedding in St Tropez.

The company can also retrieve deleted or lost data from computers, storage devices, memory cards and MP3 players and gathers evidence for county councils, housing associations and social services.

Former field intelligence detective Mr Kearns was with Warwickshire Police for more than 13 years and during that time, he realised that there was a need for a good quality commercial investigation company.

He said: "People think we are 'private eyes', but we don't deal with the private sector.

"Because it's an unregulated industry, you cannot always be sure who you are dealing with. A lot of investigators do not have the necessary background.

"But the nature of our skill level means we can do all sorts of things and put our equipment in areas where risk is quite high."

Having run the business for nine years, Mr Kearns has dealt with a wide range of cases, including one investigation into the theft of precision ball bearings - components used in aircraft and fuel control, military guidance and aerospace systems.

These were being stolen from one part of the UK, then sold elsewhere and finally shipped to the US.

Mr Kearns added: "It often happens that we end up uncovering more than the client knew about him or herself."

He admits that a common public reaction to the idea of surveillance is the fear of Britain becoming a 'Big Brother' society. But he said: "Society has made us the way we are. Ten per cent of society drains 90 per cent of our resources - they are the criminal element.

"The work we are doing is having an impact on people's lives. If we are helping to catch criminals, then using surveillance is fine in my opinion.

"If you have nothing to hide then don't worry about it."