Clematis Pruning

I have a Duchess of Edinburgh clematis and the care label says to prune lightly in spring. I also have three other similar looking clematis, but I don't know what variety they are. They are all climbing on trellis which I'm taking down for maintenance purposes. All the clematis have gone very woody and only show buds over approx 3 ft high. By how much can I prune them now?

 

Duchess of Edinburgh is an early summer flowering clematis and should be prune in early spring. To do this, first take out any weak, dead or straggly growth. Then cut back the remaining growth by about 12" (30cm) cut back to a good pair of buds. Hope this helps. David.

 

Thanks for the reply. Unfortunately I had to lop the top off the clematis when replacing the trellis so am hoping that's not going to damage the plant.
As our seasons seem to be somewhat mixed up, should we continue to follow the seasonal advice for pruning? The clematis already has good sized buds.
I'm located close to the coast in south UK and already the grass has been cut by council workmen on the village green.