Clematis and Wisteria Gone Mad

Well, not mad - but while exploring my new garden I have noticed that the clematis/wisteria/honeysuckle (not sure whats what yet) I have are growing over/through a lot of other plants.
For example I have one that is sending shoots through and over some nearby conifers and a section of beech hedge. Another is wandering over a small magnolia and heading towards another (as yet unidentified) shrub.

Is this a problem? Should I leave them to do this, or cut them back to size (and if so, when)?

 

One of my clematis, a jacmanii, went stupid last year Jesaya. In spring, when it was supposed to be putting out shoots, it did nothing. By July I had written it off and I obtained a replacement. I kept that in its large pot and didn't dig up the old one. In August it suddenly started and by October, when it should have finished, it was in flower but wasn't it's usual bushy self, rather straggly. My next door but 2 neighbour has a jacmanii as well which behaved perfectly naturally. Hers had been cut back whilst mine was in full bloom. I cut it back the week before Christmas.

I think that what do with yours is a matter of guess work. Personally, I would cut back now and hope these plants regain their equilibrium in spring. If you do cut back and it comes again immediately, I would just let it go. Again it's personal choice and if you want to leave it then it may be out of kilter but at least nature is doing its own thing.