Rosie,

I am not a Clematis expert by any means. I do have 9 or more growing in the gardens, but that doesn't really mean anything. :)

I would not cut back any plant such as a clematis at this time of year. Do wait until the spring.

Do you remember who told you to cut it back in the spring? I'm asking because of something which happened to me. I was told to do the same thing, but three years ago I neglected to cut back the one closest to our entrance. It had actually set buds quite early - much earlier than any other. To my surprise, it began blooming in early June with these huge beautiful 8 inch flowers. The name on the tag was Blue Moon, but I discovered that due to patents it was renamed Claire De Lune which is most appropriate.

Because of this experience, I discovered that my Claire De Lune blooms twice - once in June on old wood, and again in late September on new wood. So now I only cut it back after the June flush of flowers. Here's a picture which really doesn't do it justice.

{{gwi:520625}}

I guess what I'm trying to say is that you might want to let it go for a year to find out what kind it is. The folks over at the Clematis Forum are the ones who IDed this one for me as well as a couple of others. The more info you have the better.

But definitely don't cut it back at this time of year. Wait until the spring and you see movement in the growth.