Further research also exposed the shocking fact that 550,000 people (7%) said they did nothing because they were scared of the consequences.
The chronic shortage of social housing and an unaffordable housing market means now 3.4 million people in this country rent, a massive 40% rise in the past five years.
With cuts to housing benefit and changes to the homelessness safety net, Shelter is also concerned vulnerable families will be pushed into the bottom end of an unregulated private rented sector unprotected from a minority of rogue landlords who may look to cash in.
Campbell Robb, Chief Executive of Shelter said: "Throughout this campaign we have been continually shocked at the treatment tenants receive at the hands of these unscrupulous operators. What is more worrying is that this research shows just how many people are being affected by rogue landlord practice."
Further investigation revealed that 31.1 million (66%) of people surveyed, agree that they want stronger and clearer rules for landlords to protect private tenants.
Robb said: "The Government has to recognise its responsibility to protect this vast and growing population of private tenants, especially when our research has proved that Generation Rent want better rules to protect them."
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