at this stage I'd go British native possibly Mugwort. Good for nectar but not that pretty. Friend for me but you know what I am like and certainly foe for many gardeners.

Please can we have another look when the flowers are out?
(not arguing, just for my own curiosity?)

oh I totally agree. I find it frustrating when the mystery plant never reappears.

Not sure it is now so really please do let us see it in flower.