Ed Miliband is expected to point out that 3.6 million households - including one million with children - are now privately-rented accomodation.
"We cannot have two nations divided between those who own their own homes and those who rent", the Labour leader will say.
"There are too many rogue landlords and agencies either providing accommodation which is unfit or ripping off their tenants", he is set to add.
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Buckingham Palace, London's Tower Bridge, Old Trafford and Big Ben are taking part in the event to raise awareness about climate change.
Widespread frost for most areas as temperatures dip below freezing.
Premier League clubs have agreed to pay all full-time staff the living wageof £9.15 an hour in London or £7.85 an hour outside the capital.