Channel 4 News speaks to the contract cleaners at the Department for Work and Pensions who demanded a pay rise from the politician at the top, saying they can't live on the minimum wage in London.

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Iain Duncan Smith says it is his mission to make work pay. He wants to end ‘in-work poverty' So it must have been a shock to find a letter left on his desk from 64 of the people who clean his office, complaining that they cannot live on the wages they are paid by the Department for Work and Pensions (DWP).

Today I met one of the cleaners who signed that letter. She was frightened that she might get sacked if we identify her - she can't afford to lose her job, even if she can't survive on her low wages. She told me it is always a struggle to pay the bills:

"As soon as the money comes in on Friday, every two weeks, on Monday there is no money in the bank. I feel tired and depressed .. I prefer not to think about it because I want to cry."

The letter she signed said:

"Every morning we clean these offices and these hallways. Our hard work helps you to do your job properly and comfortably .. However because of our pay, we are struggling every day to buy the things we need."

The people who clean inside the DWP are employed by a private contractor, Mitie, who pays most of them the minimum wage of £6.08 an hour. But to earn what is considered a "living wage" you have to earn at least £8.30 in London, or £7.20 outside, which is what the cleaners are asking for. Mitie declined to comment on the cleaners' pay.

Felix Ojo left his job cleaning at the DWP yesterday. He let me see some of his pay slips and bank statements to show how he couldn't survive on £6.08 an hour, telling me: "at times I borrow to buy a bus pass and borrow for food. If you're borrowing how can you back it back? That is the problem - I have a lot of bad debt."

The cleaners' letter was co ordinated by London Citizens who campaign for a living wage of £8.30 for all employees in London. Matthew Bolton, a campaigner at London Citizens says:

"We believe that IDS does want to make work pay, and a lot of his policies are committed that way, to improve the incentive to work and make sure people can provide for their families. So adopting the Living Wage would be a clear demonstration of that commitment, and that would help us encourage other government departments to do the right thing too".

The cleaners asked Iain Duncan Smith for a meeting. They have not yet had a response. The Secretary of State is said to be quietly sympathetic. But the department say it would cost millions of pounds to raise the cleaners' wages.

All the staff who clean the Houses of Parliament are paid the London living wage. As are all staff at the Greater London Authority. But most government departments still pay only the minimum wage to contract cleaners. Campaigners say its time the DWP took the lead on poverty wages and finally make work pay for the people who work for them.

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