Pruning/Tidying up a Clematis Montana

Perhaps it's time to be really violent with it and cut it back halfway to the roots. I don't know where its growing from, your picture doesn't show that, but sometimes, every few years, its better to hack it back to half its size, removing all that dead brown wood, and letting it regrow. That probably means it won't be over the door, but it will regrow, usually with a vengeance!

Thanks for your advice. I hadn't thought of going halfway back. I just thought all or nothing! Halfway back sounds good. The photo shows it going off to the right. It's planted to the left of the front door and goes off to the left over the kitchen window. I have a euonymous planted in front of it which is climbing through it and that's lovely - I'd hate to have to cut that back too so half way sounds ideal for me.