A few more ideas on pruning can be found in the article on Pruning Roses, on Bexrose web site at:-
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Martin Double Bexrose - Webmaster
Yes, most roses do go dormant in the winter, and winter is normally
> the best time to prune. I'm not sure what your frost dates are, but
> try to prune after the last hard frost, so you can see what all the
> dieback will be, but before the new shoots come out.