Leave them until shoots appear at the base in Spring before cutting back. You will then see which is the live wood, and the top growth will protect the crowns through the winter.

Thanks for that very much appreciated, as a novice still!!Andrew

that is exactly what I was going to say too.
after a harsh winter they may totally die down and regrow from before soil level. I thought I'd lost some 10yrs ago and luckily I didn't get round to removing them until late April and much to my surprise I had new shoots.

I think that is how I left them last year but I have been told that I should be harsh and cut back, truth I don't have the heart as they look really healthy despite the onset of colder weather, just worried if I leave them they will get a bit "leggy" when what I am hoping for is for them to flourish into a more prominent bush. Thanks for your advice. Andrew.

You can do your harsh cutback later as recommended above by all of us!

The harsh winter weather in March last year was a shock to us all. I have got everything covered in fleece ready for it
this year.
Have a Fuchsia in a £1 bird cage from the recycling centre (its a joke!) standing on the floor of the greenhouse. Must cover that too. Also find the old sacks to cover the
Polyanthus plants in the shower base. They loved that last year.

Your profile doesn't say where you live Andrew. Its only in quite mild climates that the top growth will survive from year to year to make a bigger bush. We are comparatively mild here and none of mine have ever made it. But they do grow quickly again in spring once they get going and the bush does increase in size as it matures.