I can't thank you enough for all your support and advice today, you have been wonderful. You were so right, she came and let us know in her own way that she was ready for him to go. Now she is flopped out and has stopped searching for him, it is a comfort to see her at peace instead of hunting for him.
Tonight I have sent a tentative email to the local rescues I know about (we are in Scotland) including the one we got Monkey from to start the search for the right boy for her.