By Katie Barnfield: ITV News London reporter
Having interviewed tenants on housing benefits before, I knew that calling round estate agents trying to find properties to rent to them was going to be difficult. What I wasn't prepared for was how bad the situation really is.
I called 50 different agents across London, asking about two bedroom properties - something that might be suitable for a single mum and a young son for instance. I was asking about the cheapest properties available in each area - and yet, hardly any were available at all.
Out of every estate agent I called, I could only find four properties where the landlord would even consider a benefit claimant as a tenant.
Only one of these would consider them without a guarantor - that's someone who agrees to cover all of the rent if for any reason you fall behind. One of them told me I'd need a guarantor earning £43,000 year to rent a property which cost just £1,100 a month.
The situation didn't change whether it was someone paying all of their rent through benefits, or someone who was working but whose income didn't quite stretch to the level of rent you need in London. With most properties I looked at costing well over £1,000 a month, this will be a lot of people - especially when you factor in the cost of things like childcare.
One estate agent told me they hadn't had a property on their books which was available to a benefit claimant in seven years. Another said about a particular landlady: 'even if you were the Pope and you were on benefits, she wouldn't rent to you'.
Mary Wilde is just one of those benefit claimants who have struggled to find a place to live. She was told to pay over six thousand pounds in rent and fees upfront, because she couldn't find a guarantor earning over £28,000. She says she felt pressured to pay, because she couldn't find anywhere else available to her.
To put all of this in perspective, looking on Spareroom.com for properties to rent in London, on the day I checked there were over 2,300 available. When you tick the box which says 'Housing Benefit Considered' the number drops to 73. Spareroom told me they'd added this feature to try and make it easier, not harder for benefit claimants - but they'll now be reviewing it.
Both Rightmove and Zoopla say they've banned adverts with the term 'No DSS' in them - an old, and common way of referring to housing benefit. But when I looked on both sites, these terms were still clearly visible in some adverts.
At the moment, this practice is not specifically banned in the law.
The housing charity Shelter is planning to take some cases to court this summer, arguing that it may contravene the Equality Act because it's often women - single mums for instance - and disabled people who are claiming benefits.
The Work and Pensions Select Committee also met at the end of last month discussing this issue and are due to make their recommendations soon.
Many charities - and London's Mayor - are calling for a change in the law. While the situation stays as it is, for many vulnerable people in London finding a home is simply impossible.