well hello stranger, how are you? lovely to see you back.
Spring before growth starts is your best bet. it is an elder so you can be rather brutal if you need to be. if the shoots are very green rather than a touch of green below the darker colour, they need taking out totally.

Hello Seaburn, pleased you are still around too ! I’m fine on the whole, getting a bit arthritic in my old age ! Makes it difficult to garden as I would like but enjoy what I am able to do.
Thanks for info. I have had it a couple of years but it is going a bit mad now. I’m afraid if I cut it back hard now I shall have to sacrifice next years flowers.

I thought they flowered on new wood.
the RHS say its pruning group one

https://www.rhs.org.uk/advice/profile?pid=954

I'm retired now and do lots of gardening , sewing and biking with my hubby.

That’s lovely Eileen, I’ve been fine till quite recently, but I’m happy,
It’s lovely to be able to share your hobby isn’t it.

I take mine back to two foot stumps in early spring, just as the growth starts, and it still carries flowers later in the year

Oh thank you Andrew, that’s just what I needed to know. It must be too late to do that now, do you think ?

Yes, I'd wait until next year now

Thanks Andrew, will do that.