Are you saying there's no topgrowth at all, or that there is topgrowth but much of it is damaged? Any chance of a photograph please? As for slugs and snails, regular application of pellets is required, particularly after rain (if you haven't used rain proof ones) but only a few at a time.

There is/was topgrowth which was doing rather well when I re-planted it; there were 2 vines of 18 ins and 2 ft tall. One vine was destroyed hence the use of slug pellets, but last night there was sign the 2nd was being attacked. when I replanted I was really pleased with the roots. I don't have a picture immediately to hand.

I've had to chop two of my clematis down to their bases, one because of mildew and the other which was caught in the drift of some weed killer I sprayed. They are both doing wonderfully since I moved them and are putting on a lot of growth. However, the slugs would have had a field day had I not kept putting down the pellets.

It's certainly worth keeping it - I've known clematis in the ground to disappear completely for various reasons and then reappear the following year. In all this, though, you've not said which variety of clematis it is, do you know?

Thanks for the advice.I used slug pellets, and have been watering the plant nearly every day. As a result the remaining vine is doing brilliantly and there are signs it is about to come into flower.