In message , K
writes
As I'm trying to be Organic is there anything I can do to stop this ?
What is likely to be doing this , slugs ?, snail ?, caterpillers ?

Slugs and snails. They love clematis. Once they're established (ie high
into the trees) they're OK, but getting there is a problem.

Do I need to go out at night with a torch and catch the little B****rs
that are doing this ?

Yes, if you want to be organic.

Had the same problem (though I suspected earwigs). Made a sort of tube
out of flypaper - hard to get, but you can still find it, and very
sticky and fiddly, but it worked! Nothing will go across it! Of course,
you have to water with care and go through the whole sticky business
again if it rains too much.

--
Klara, Gatwick basin