Thousands of vulnerable people are housed and supported by not-for-profit social housing providers, many of them charities. Panorama investigates one charity and its links to a millionaire developer who has turned taxpayer-funded housing benefit into a personal fortune through the supply of properties. Reporter Rory Carson speaks to tenants who feel they've been let down by the charity, former employees who say serious problems of anti-social behaviour were sparked by the charity's focus on expansion and hears calls for better regulation of social housing to protect both tenants and the taxpayer.