The rampant clematis I hacked back on a strangely hot day last spring (on my day of UCU industrial action) looks like it is a Clematis cirrhosa, possibly var. balearica. This is a winter-flowering, evergreen clematis - though it hardly ever seems to be without a few flowers. This winter has been mild and there have been a few hidden-away flowers for some time already. The flowers are very pretty bell-shaped, dusky pink on the outside with delicate dark pink/reddish flowers inside. But because they hang down and are few and far between they are not very noticeable most of the time. It would be better grown up a pyramid or pergola so that the flowers are above eye height.
Pruning: This type of clematis can be pruned in spring, immediately after the flowers have finished, usually March. It can be pruned to 1m above the ground.
The roots and base of the plant should be kept in the shade.
It likes a mulch of compost around the base in late winter, avoiding the crown.
RHS - Clematis Cirrhosa