Yes, because of the photos you and Andy have posted, I'm thinking this is a British tree... Are they good for anything after they drop? They're quite a pretty surprise within that spiny exterior!
I absolutely *love* that you created garden art out of these! I once created a piece of garden art in a class, the notion being that in time it would disintegrate (and become all-the-more charming looking!) Sounds as though these will be with you for some time...worth the effort!