This looks like Arabella which is a herbacious clematis and flowers continuously during the summer-if its a climber then it won't be Arabella.

Thanks for the response Pixie. It is a climber. there are dozens of photos on Google of clematis similar to this but I can't find one which exactly matches.

I agree, looks exactly like the Arabella we have at work.

I have one that looks like that. The flowers are quite small and it flowers for a long time. Mine is called Justa, and it is a climber.

Thanks for the info Gaia . I've googled but there are various clematis called Justa on Google some with 8 petals and others with 6 so I wonder wonder which is the correct one! My photo has 6! There are dozens of very similar clematis on google but I cannot find an exact match :(

Clematis Perle D ' Azur ?

Could be but I'm not totallly sure. Thanks for your help

Try perryhillnurseries/catalogue/climbers/clematis/perle d azur for photo if trying to ID by photos .If it were an ID parade I d swear it were similar lol

According to Google the flowers of Perle D'azur are 5-6 inches. My neighbours clematis has flowers only 2 inches across.

Here is another very good identification site www.clematis.hull.ac.uk

i've just had a look but unless I've missed it you can't add the flower diameter as a parameter of the search so I'm getting dozens of similar flowers but most are much bigger. Thanks for the link though. I'll save it for future use. :^)

it looks so much like my multi blue's later flowering, that is now out as a single. But it is a slightly bluer colour than mine.
I sometimes have difficulties naming some of my varieties. I take cuttings from other folks plants and they are never identical, because of location compared to the original parent plant.