That's such a pretty garden, Neil. I wanted to go to the open days this weekend and planter's palette but had to work. Maybe you could start another thread with some of the pictures you took of the gardens.

Another closeup of flowers, has a hint of really light blue in the flowers. Also buds on top right

Thanks for the feedback. After checking other photos and details for the plant I am sure you nailed it. In Michigan it is actually considered a Noxious weed and quite toxic to livestock, especially horses; in Europe it is considered an ornamental plant good for landscaping purposes so I guess I will still include it in my collection of wildflowers even though most people in Mich. might disagree.

Yep, Carol is right. The NY Flora Atlas does have images for most of its species list. It is a really nice resource for NYS'ers so save the link. Sorry I botched the original URL and thanks to Carol for sharing a correct one.