A significant number of people become landlords accidentally, according to one expert.
Chris Horne, editor of Property Hawk, said that such property owners often enter the market by letting their property when their domestic circumstances change, such as remarrying.
Similarly, Mr Horne suggested that people sometimes inherit properties and choose to rent them out instead of selling them on.
"I term them accidental landlords [because they] haven't actually set out as such to become a buy to let investor, but through circumstances have ended up with a property and decided to keep it rather than selling it," he said.
According to Mr Horne, for accidental landlords the buy-to-let sector represents a "low-risk" investment, as they are less vulnerable to house price fluctuations than other property owners.
Recent research by the Association of letting Agents found 19 per cent of landlords have been in that role for year or less, while a further 41 per cent own two or less properties.
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