This one is interesting as I'm about to buy one.
Buy to let is exactly the issue. Has been for a while and it's got quite serious. It's nothing more than landlords buying up all the properties and then renting them back out at twice (or higher) the mortgagable rate to make profit.
I just moved from a 2 bed apartment in a 3 apartment/3 shop complex paying £600 a month, to a full 3 bed semi-detached house with front and rear gardens and drive/garage.... Mortgage + rates = £550 a month.
But those on lesser income will not get a mortgage so they get stuck paying higher and higher rents. Calls to regulate the landlord business to cap rents and force landlords to provide "quality of service" and "minimal living standards" in their properties, was voted out in parliament. Everyone of the Tories who voted against it... you guessed it... have multiple properties to let. No conflict of interest at all. I want that vote taken again, but anyone who has a for-let property be banned from voting.
With the UK crawling further and further into bed with the US and with Brexit removing very rapidly our human rights bill and employement rights this will just get worse. When the employement rights go getting a mortgage will become much, much harder, so only the affluent will have the capital to leverage a mortgage, meaning the rich will own all the property and the poor will pay rent and jump to their landlords whim.