The Clematis is the second flush of flowers on C. sieboldii. The other white Clematis early on is C. montana wilsoni and the one right at the end of the posting is unknown to us as it was bought as Jacqueline Dupres which it is not.
Glad you enjoyed the tour.
Sorry Martin, but we do not get these pop up ads so I never think about them. Ad Blocker plus for Firefox is very useful.