So many questions and so many assumptions.
I use the term flatmate to keep it simple. Technically the couple are sub-letting month to month and this is the reason they can be asked to move out with only short notice. They do not have a lease. By law they are not lodgers.
When I leased the house I was handed one set of keys. I cut and paid for a spare set for me and another for a 'flatmate'. I am not legally bound to supply a 2nd key, they are free to cut as many keys as they want for their own use.
When advertising the room it was listed for a single female sharer. The female was couch surfing (living out of a suitcase) with various friends and desperate for somewhere to live. She was not being accepted anywhere as she had lost her job. I agreed to her (and then her partner) to stay for 3-4 months until they got on their feet. (TBH preferred to have 1 flatmate only) Did not charge them any extra for the male partner, just for him to pay his share of utilities. Looked at the situation as doing something kind to help young people get their life back on track. It is six months and they are still here, guess they are happy.
Back to yesterday. He left around 10.30am and returned just before 4pm. Wouldn't you think he would find out what my plans for the day were before risking going out for hours without a key? I left soon after he arrived home to babysit my grandchildren for the night.
I asked why they did not have a key cut for his use. His reply was that he didn't know if it was the special type of key that requires permission to be copied. When I asked what what the key cutting place said, it turns out he didn't bother to ask anyone. Our keys are regular keys - there is nothing to suggest that they are "Do Not Copy". Who called him a man-child?
TheBeast. Thank you for the link - looks brilliant but I am renting.