It has taken a while, but I do now have some understanding of why they were so excited. I guess it's not everyday that, while clearing junk from under a sink, you find a tea set recording a part of your own history. I was sure it would turn up somewhere in the centre. I didn't believe it had been re-donated - life just isn't like that. It is just much more likely that things get lost for a bit and then turn up, particularly in places where funding - and therefore workers - come and go like changes in the weather.
I'm hugely grateful to everyone at the centre and to their two resident PhD students, who are researching the centre's history, for the considerable trouble to took to trace me and let me know that it was, after all, still there. I'm also grateful they took the trouble to communicate their enthusiasm for tea set to me - it has reminded me why I made it in the first place.