You may find an answer if you look back over some of the questions asked quite recently. I seem to remember there was an answer not long ago to that sort of question.

Hi Bryony, I pruned mine hard one year very late and all that happened was it flowered late, so I'd go ahead. Mine was a lochinch by the way:-)

I only managed to get mine done last week,as I couldn't get the back gate open,to get to it.I'm sure it should be fine,and yes,cut it hard back .As Bornagain says,it will just flower later.You will see new leaves appearing low down,so cut above them.