If someone living in accommodation they are renting sublets it or a room illegally, and I enter a contract with them for that accommodation, what repercussions could there be later?
I found this advice https://www.citizensadvice.org.uk/housing/renting-a-home/subletting-and-lodging/subletting/what-happens-if-a-subtenancy-is-unlawful/
If they weren't allowed to sublet because their tenancy agreement said they couldn't, or if they didn't get their landlord's permission beforehand when they should have done, this means that the subletting itself is unlawful.
However, even if the subletting is unlawful this doesn't affect your tenancy. Your tenancy is valid because your landlord, who is the mesne tenant, created a tenancy - your subtenancy. This brings about a relationship of landlord and tenant between you and them.
Which I don't understand. Sounds like the subletting original tenant is contractually obliged to provide me the accommodation, but how can they be allowed to continue to do that since it's illegal in the first place?
What would really happen if they were exposed?