New research shows that one million homes, which were owner-occupied in 2005, are now owned by a landlord. This accounts for half of the growth in rented stock (since 2005).
In the same period, over two million homes have changed tenure, when taking into account all property sales between owner-occupiers and landlords, the research from Countrywide plc reveals.
Some 1,550,000 properties have gone from being lived in by their owner to being lived in by a tenant.
There has been movement the other way too with 550,000 properties moving from the private rented sector into owner occupation.
The result: an extra million homes are now occupied by a tenant rather than homeowners, equivalent to the number of households in the North East of England.
This transfer of owner-occupied homes into the private rented sector accounts for half of the growth of rented stock.
The remaining growth can be accounted for by landlords buying newly-built homes.
Since 2005, 700,000 new homes have become part of the the private rented sector, while residential conversions and social housing account for the remaining homes which have changed tenure.
Even so, homes are only half as likely to change tenure as people.
65% of homes that leave the private rented sector are picked up by first time buyers.
Over the past twelve months, 15% of first time buyers climbed on to the housing ladder in this way.
That is the equivalent of 45,000 first-time buyers buying their new homes from a landlord, which is the largest figure since the 2008 downturn.
Landlords and first time buyers are more likely to be on the look out for smaller, cheaper properties, hence the fact that they often find themselves in competition with one another.
Consequentially, they are disproportionately likely to buy and sell from one another.
London and the South East are the two regions where the private rented sector is most buoyant.
It is therefore in these areas where first time buyers are more likely to purchase an ex-rental property.
One in five new buyers in London, and one in six in the South East, bought a home which had previously been rented out.
It is also in these two regions where the difference between what new buyers paid when buying from a landlord and those that didn't is greatest.
On average those buying from a landlord paid 8% less than those that didn't.
Johnny Morris, director of research at Countrywide, said:
"The rapid growth of the private rented sector has to come from somewhere, while the tenure may change, the physical home remains. The sector has been growing since 2005 but the number of homeowners has fallen in each of the past 10 years.
"This scale of shift in tenure shows that the current push from the government to increase the number of homeowners is unlikely to be enough to reverse the decline.
"Although landlords and first-time buyers might not appear natural bedfellows, because they tend to look for similar types of homes they do end up selling to each other. Many landlords face a choice 10 to 15 years after buying a home, between refurbishing the property or selling it.
"Those landlords who choose to sell up offer an opportunity to first-time buyers willing to put some work into their first home, often adding to its value.
"Rents grew by 4.8% over the year, supported by the imbalance between growing tenant demand and constrained supply of homes to rent. The usual seasonal factors are seeing small month on month falls after as the summer rush continues to subside."