You would typically be an excluded occupier, meaning that you could be evicted with only "reasonable notice" - typically seven days. The landlord doesn't have to give a reason, you have no right to appeal and the police can remove you if you refuse to leave.

https://england.shelter.org.uk/housing_advice/private_rentin...

I didn't notice in the article that "they signed a lease/contract".

"He signed the check in a messy scrawl" but not a contract.

In the UK (and many other parts of the world) a contract is (almost) always signed before anyone moves in. Handing a checque means nothing is not bulletproof. One can claim that it was a payment for a selling an old computer (and then the courts will have to do the talking).

But this was a roommate situation. I doubt most people sign any formal letters when hiring a roommate, as most people don’t come from a legal / business background.

He also handed a check instantly to people who were desperate for money...