The number of buy to let homeowners could double in the next three years, according to market research group Mintel.

Around 3% of homeowners are thinking of buying a second property to rent out by 2010, which would approximately double the number of private landlords in the UK to 2 million.

Mintel said that the trend towards buy to let ownership will be driven by a big increase in the population, partly fuelled by immigration, and the demand for rented accommodation as many are kept off the housing ladder by high prices.

“Increasingly, property owners are seeing the benefits of investing in bricks and mortar and often regard the second homes market as a good alternative means of saving for retirement,” said Paul Davies of Mintel.

“As long as these trends continue, future growth in this market should be guaranteed.”

At the end of last year there were 850,000 buy to let mortgages taken out, constituting 9% of all mortgages secured on UK property.

According to Mintel’s survey of about 2,000 adults, 68% of people with second homes believe their properties are better investments than pensions.

Asked about another possible leap in interest rates, only 10% of the respondents said that this would be a factor that may put them off investing in buy to let.