Living it up on benefits – we’ve all seen the footage. The woman who said she needed a wheelchair dancing the night away at a wedding. The police officer off sick with a bad back, running hell for leather at five-a-side.

Successive governments have struggled with a spiralling disability benefit bill. It currently stands at £13 billion a year.

But, for the coalition, it’s about more than the cost. It’s about a culture which they believe has grown out of a system that leaves people ‘languishing on benefits’.

The Prime Minister is direct – it is a ‘sick note culture’, and he’s vowed to end it. At the heart of his crusade stands a French multinational company, Atos. It has been given the task of assessing just who should be on Employment Support Allowance (which replaced incapacity benefit) and who should be heading back to work. Their contract for this is worth a £100 million pounds a year.

From the beginning, the tests – known as the Work Capability Assessment – have been enormously controversial. Claimants have been unhappy with the questions they’ve been asked, the way they’ve been handled by assessors and, crucially, the decisions which have been made by the DWP based on the assessments.

But no one has been able to give an insight into what goes on from the inside – until now. Dispatches has gone undercover at Atos.

GP Dr Steve Bick agreed to go undercover and become an assessor at the company. While training he’s told more than once to understand the new Employment Support Allowance process is ‘meant to take people off benefit’.

Despite repeated claims by the government and Atos that there are no targets for taking claimants off benefit, it’s made clear to Dr Bick that if he finds too many people unfit for work, his own assessments will be monitored.

The trainer explains: ‘You are being watched carefully for the rate of support group (people found unfit for work and therefore eligible for the highest level of ESA). If it’s more than, I think, 12 or 13 percent you will be fed back ‘your rate is too high’.’

It’s a view repeated later in the footage by another doctor who says the targets come from the Department for Work and Pensions – a claim once again denied by the government and by Atos.

The footage also suggests just how tough it is to be found ‘unfit for work’. The trainer talks through how people with a disability affecting their arms must be assessed: ‘If they have one problem, one frozen shoulder, one impeachment syndrome, one broken elbow, one hand problem , no limb, amputation, they may score a little but the problem has to be bilateral’. She goes on to concede that it’s a ‘very, very tough benefit’.

How tough is made clear when Dr Bick asks what sort of job someone with only one hand might be able to do. The trainer elaborates: ‘As long as you’ve got one finger and you can press a button you don’t score anything for manual dexterity’.

The Department for Work and Pensions refused to give an interview to Dispatches. They take issue with Dr Bick’s role in the film. He stood as parliamentary candidate for the Labour party in 2010.

But what about what Dr Bick found in a system which, after all, was first introduced by Labour. In a statement the DWP said when the system was assessed two years ago it was not ‘entirely fit for purpose but has since been significantly improved’.

Atos said that independent reviews confirm they are providing a high standard of work, but that it is there duty to look for ways to improve. They also said, ‘We invest time and resource in training and reviewing the work of our medical professionals to ensure that those assessed are treated professionally and sympathetically’.

Nearly half of all claimants appeal against the assessments and almost a third of those appeals are successful – a figure the DWP is determined to reduce.

Professor Stephen Bevan, a director at the Work Foundation, believes the principle behind the assessments is absolutely right. But the footage, he says, gives him real cause for concern. ‘The danger is you are almost treating people a bit like a car going through an MOT with a sort of tick list and I think that reduces people down to a set of physical symptoms rather than the whole person’.

His biggest fear is that the government’s avowed intention of the Work Capability Assessments – to genuinely find out what disabled or ill people are capable of doing in the workplace – is being overwhelmed by a desire to cut benefit costs.

He says: ‘There is a real worry that there’s a presumption of malingering or some sort of dishonesty going on here, which I think is a real shame because all our work shows that the majority of people with often very severe and disabling conditions really want to work and have got an amazing amount to contribute to work’.

To watch the footage of the show please click here to watch on 4OD