A few hours ago (at around 1am) we could hear this cat making loud distressing sounds repeatedly. We looked outside and saw it on our garden wall and tried to help it. We fed it some tinned tuna we had lying around and it ate around half of the tin.

The cat walked into our kitchen and had a look around. The cat seems to be friendly with people but wasn't so sure of us so we were careful not to spook it. When she was a bit more familiar with us she rubbed our legs and let me gently pat her head.

We think we've identified her as a female and she only has one eye. She also has a wound on her right side that doesn't seem to look fresh but not too old either, we're not too sure what it is (fight maybe?). She looks decently fed and doesn't look too ungroomed, but we think she might have fleas as she was constantly licking herself.

What should we do? We're students living in Sheffield, UK and plan to phone RSPCA tomorrow morning if she's still hanging around. We're hoping the food and small amount of attention we gave her entices her to come back so we can get her more help. We also put a small cardboard box on its side in the garden and left the rest of the tuna in there with a bit of paper roll as bedding, its all we have ☹️. Is there anything else we can do in the mean time? We can't keep her in the house as we technically aren't allowed pets and we also can't risk any potential fleas getting into carpets or anything. I'm just hoping she will be okay for a day or two while we try to get RSPCA to come help.

Any advice is appreciated.

Unknown cat appeared in back garden