All I can offer is to say it is a clematis but I have no idea of the variety!

But it's a nice one!

Thanks Teegee I meant to say it was a clematis, it has been in the garden for ages but this is the best year ever, it must have been all that rain. Lol !

Jackmanii? Or The President? Not good at clematis, but I'm sure someone here will know what lovely variety that is.

I'm afraid I don't know what variety it is either but you may be able to search for it on this website:

http://www.clematis.hull.ac.uk/index.cfm

I thought 'The President' too because it looks exactly like mine although I haven't checked the number of petals (it's dark out there!) If so, the individual flowers seem to have longer stems than many others.

Looks a bit dark to be The President - Violet Charm?

Thank you all for your responses, I will search the website.