Thanks @MServant.I hope his new furever home is loving being taken over by him and he is one happy kitty guy right now. Must be hard letting them go.
YES, it's awfully hard letting them go, after you've gained their trust and affection. And it's awful for them in the first place that their life has to be turned upside down because something has gone wrong with their human carers. When they reach their foster home, I expect they think they can settle, and then it's a big, stressful upheaval again. Still, it's better than the alternatives, and you've got to remind yourself of that.
Many thanks for your help and encouragement along the way, @MServant.