I know it is difficult to ID many plants from a picture as pictures of the same variety often differ so much but this one is so lovely I thought I would give you plant detectives a try. I remember it being a little bluer. This is in a neighbors garden and they didn't remember the name.

It's a beauty Paul! I think you will struggle to find which one it is unless your neighbour has strashed the label somewhere, you could try asking if they keep labels. Maybe there's a local seller who knows which ones have been sold in recent years.

You can search on a Clematis site here but in this case all you can really search for is 'blue' for tepals and 'cream' for anthers which brings up a few, more if you only search for blue and several look so much like it.

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