SOCIAL tenants were left mourning the end of their secure tenancies outside Parliament yesterday as the Commons looked set to pass the Housing Bill at its third reading.   Members of over 70 organisations have backed their campaign against the Bill, which they say would “end social housing forever.”   Experts who were out lobbying MPs yesterday warned that the government’s housing plans could lead to another subprime mortgage crisis like the one that started 2008’s financial crash.   Architects for Social Housing co-founder and protest organiser Simon Elmer told the Star he hoped housing activists would unite to form a new anti-Poll Tax-style movement.   The Bill is dangerous, Mr Elmer said, because it puts the definition of what constitutes high-value property or an affordable home in the hands of Communities Secretary Greg Clark.   “It’s all at the discretion of the secretary of state, who is becoming this housing tsar,” Mr Elmer warned.   The campaigner also criticised Prime Minister David Cameron’s new house-building scheme because the homes would be managed by private developers and put up for sale at prices most low-income families could not afford.    Islington homeless man Ray Hayse told yesterday’s rally that the council had rejected his housing application.    “I have mental health problems but they said I wasn’t vulnerable enough,” he recounted.   “My private house was taken away and turned into students’ accommodation and they did not have to give a reason why I was evicted.    “What I don’t understand is that under [international] law everyone has the right to a home. This government is ridiculous.”   The only MP at the rally was the Green Party’s Caroline Lucas, who vowed to oppose the Bill.    “The housing crisis is biting hard. Renting is unaffordable, our social housing stock is dwindling and buying a home is still an impossible dream for many,” she said.   “The Bill should have looked at ways to make rents fall — but it doesn’t even go as far as bringing in smart rent controls to keep them in line with inflation.”