It was difficult. It was hard. It was the best decision I could have taken. Because I've decided he's not coming with me to Norway. Mr Pepperfly and Peppermaggot are overjoyed! They had already been plotting several things: like changing the locks, moving, bolting the door, hiding him. In the end there was no need. I made the decision on my own.
There are several reasons for my decision. First of all is his age. He is 15, which is older than most outside cats ever see. Second (and related to his age): do I really want to uproot him again. And to a home with no other playmates and no other humans beside me. And third: did I want to get him because I wanted to give him a better life, or just because I wanted him with me? And the answer was I wanted him with me.
He has a great life. He has a playmate called Mickey, another called Linette and three humans who love him to bits and were not pleased about loosing him (hence the plotting against me). He can go outside and watch the bunnies. He can come inside after only 10 minutes. He gets to sleep in a bed and basically: he's happy.
So, I will be going home again cat-less and a little sorry. But in the knowledge I have done the best thing.