When in UK is the best time to prune roses?

And how far do you prune back?

They are still in full bloom and many buds but now we are starting to get night frosts.

Hi

In order to prune your roses you should:

Have a good set of secateurs - to avoid bad cuts.
Make a sloping cut
Cutting bushes, you should cut out the dead wood and weak spindly shoots.

If you need more information on pruning you plants, there is some good info on Apuldram Roses.

Thanks for useful link.