Venosa violacea, maybe?

It reminds me somewhat of ' Asao' , a large flowered Clematis.
Try posting on the Clematis forum for an ID.

Thanks guy's, it does seem most like Asao but I planted it (and stupidly didn't label it) and the name Asao isn't ringing any bells. I have posted it on the Clematis forum now.

It probably isn't Venosa violacea because that blooms later than forget-me-nots, here in July and August.

One way to help ID clems is to use the search page on Clematis on the Web, linked below. Fill in the info you know.
prune: type2 based on flowering time
group: early large flowered
tepal color: pink
and leave the stuff you don't know blank. Then look at the photos of what pops up to see if you can ID it.

It does look about right for Asao to me also.

Here is a link that might be useful: Clematis on the Web search page

Thanks nhbabs, I used the link and the closest match is definitely Asao, really appreciate your help, lesson learned - label everything.