It seems to me that there's no point in buying a house that one can't use, either because there are people living in it that one doesn't want there at all, or because one doesn't want them as tenants because they don't pay their rent. There must be sellers who try to sell precisely because they know that they have bad tenants or random people occupying their property, and they don't want to deal with that through the formal chanels, and see the sale as their less arduous way out of a bad situation.
This is what I understood, too.
How to avoid this miserable situation? As far as I know, unless the buyer wants to take over existing contracts with existing tenants, there ought to be a clause in the contract expressly saying that the seller is responsible for "vacant occupation". That would mean that the seller is 100% responsible for getting all tenants/occupiers out of the premises, not the buyer's problem in any way.
The part I don't understand is how to hold the seller to causing this to come into effect.
By when must the seller undertake this?
Is there a penalty if the seller does not?
Is there a recommended way to put this into the OTP, such that, if the tenants or occupiers won't budge, the deal falls through, and the buyer is free to move on, undamaged?