There is a cat that sits outsides meowing very loudly when i opened the door to see what was wrong the cat ran in and started humping my spayed cat - is this normal ?

whats your cat look like

My female used to get this from a neighbouring Tom who just refused to believe that she was speyed. It would often end in a fight and my female always came off worse unfortunately.

Do you know whos tom it is?

No idea I think it could be a stray. So even though she is spayed male cats can still tell its a girl?

Yes, sometimes a Tom cat will try to mate, even though the queen is not giving any signals I am suprised she let him though.

The tom cat is still sat meowing outside and has done all day - when will he stop? Is there a mating season or will he always be after my cat?