A jobseeker claims he was left suicidal after being made homeless when Kingston Council failed to inform him they would not be backdating his housing benefits.
Steve Thomas, 54, was 11 months in rent arrears when he was kicked out of his home in Beaufort Road in March 2014, where he had lived for 20 years.
His landlord had evicted him after realising months later that Kingston Council had not paid up on his behalf.
Mr Thomas said he did not receive two previous council letters asking him to prove his status before completely stopping his benefits.
He appealed to the Local Government Ombudsman, who found fault in the council’s failure to formally confirm its decision not to backdate the housing benefit between September 2011 and October 2012. Mr Thomas said: "I could not believe it.
"I did not get any information until 11 months later when my landlord told me - and then he puts a padlock on my door and locks me out.
"I was sleeping in a friend’s tent - in a back garden. I was sleeping rough and I was homeless for four months. I was in a bad way. My stress levels went up and I really lost the will to live.
"I started feeling like everything was going wrong. I lost my friends and family. I lost a lot of my stuff."
Mr Thomas, a former electrician who has been unemployed for 17 years, now lives at the YMCA in Surbiton and is on anti-depressants.
He said his severe dyslexia has prevented him from finding work in his profession, and he is unable to pay for up-to-date electrical training.
He plans to work as a volunteer and a gardener in the future.
The Ombudsman’s final decision, published in June, said: "There is a fault by the council because it did not formally confirm its decision not to backdate [Mr Thomas'] housing benefit."
However, the Ombudsman accepted the council's submission that housing benefit can only be backdated for six months from the date of request for people of working age.
A Kingston Council spokesman said: "The council accepts the Ombudsman’s finding that it did not issue Mr Thomas with a formal notice denying a request to backdate his benefit claim.
"It is clear that the council acted in accordance with the Housing Benefit Regulations and this was endorsed by the Ombudsman.
"Despite the council writing to Mr Thomas on several occasions inviting him to make a claim for housing benefit he failed to do so within the appropriate timescales.
"It was over a year later, in October 2012, that he finally submitted an application form.
"Therefore, the council cannot be held responsible for his delay in applying for housing benefit at the appropriate time."