I have 7 Clematis and one (an 10-12 year old) has brown spots on the leaves and I am assuming its a virus? some travel down inside the stem to the roots? I have removed all the affected leaves and sprayed it twice and today I saw more leaves are affected. The plant is covered in lovely blooms which look fine? I water only round the plant and not on it, but things suddenly happen with Clematis? Hopefully someone can tell us both more?

Oh dear, that doesn't sound too good does it. Lets hope someone can help. Like you, the flowers and growth of the plant is good

I had wilt on this one in the first 2-3 years and each time I cut it right back. Not had any problems for over 5 years until now?

I've not had any problem with this one, but this year it has gone mad growth wise. The soil is not very good where it is either.

There are leaf spots which affect almost every plant there is. Unless the spots have yellow concentric rings around the black area and the leaves are otherwise malformed then it is just a fairly normal, if unsightly fungal attack. If it was a virus then the plant would begin to look unthrifty generally, not to be growing well as you describe.
Soak with a good systemic fungicide and remove the worst affected leaves.
If the plant begins to droop (from the top) and there is no sign of snail damage at the base of the stem and inside the stem is 'black' then it is Clematis wilt for which there is no cure except to cut out the affected stems down to ground level.

Thank you very much Owdboggy. I don't think it can be anything that serious really, seeing as the plant is making so much growth. I was tempted to cut it right down, but maybe that would be a bit drastic at this stage, unless of course I notice it wilts. Thanks again

Thanks from me too OB that has cheered me as I am fond of this plant.

Been looking at some of our alpinas and they have a few leaves like this on them, but the growth is good and strong. It could just be the dryness and strong sun. At least with alpinas, now is the time to prune them if you must.
We have over 100 clematis by the way.

Good Gracious ! You must have a very large garden Owdboggy. I don't really want to cut mine down yet as it has only been flowering a couple of weeks, so just won't look at the leaves for the time being. Where it is growing is in the sun and very dry too so that is probably the reason then.