No is the answer. But if there is a C. macropetala within bee distance then you can get a cross between the two. C. macropetala is the American version of C.alpina, they are very closely related.

You've saved my sanity, Owdboggy. Thanks very much for the explanation.

We have a C. ?macropetala which grew in my Alpine House, it flowered this year and is the sptting image of C. m. Purple Spider. Now there is no way I would sow the seeds of this or any other Clematis in the hyper-tufa crevice garden in the Alpine house, and we have not got Purple Spider in the garden any way, so you tell me! Nice plant you have there though.

Yes, it's very pretty and lots of flowers. Perhaps the bees just happened to cross the same two plants as the breeders did - it must look a bit out of place where it is, lol.