I would say that its had its day. It looks as though its been grafted but with a little investigation it would seem that the lower growth could be coming from the roots. Having said, you could be a little drastic and reduce the whole plant to about 3 feet (above where the stem branches four ways) just above any discernible, outward-facing buds and give it a go.

this is the RHS advice:

https://www.rhs.org.uk/plants/details?plantid=778 this is general info

https://www.rhs.org.uk/advice/profile?PID=197 this is pruning advice

I have seen this many times, where Exochorda is planted too close to other shrubs, this is a shrub that does need a decent space to be appreciated, it is quite graceful with its longish arching stems, normally you would trim this back after flowering in the spring, but sometimes you have to start again and that’s when renovation pruning can be carried out, I think it looks awkward in its growth, so carefully you could cut back the top growth to leave a frame work for it to start again, or go lower, it will respond or judging by its size it should move quite easily which if it were me then that’s what I would do, it’s far too close to the mahonia and camellia, these both respond well to hard or renovation pruning if in the future you needed to.

Hello,

Thanks for your comments.

I've added another photo so you can see the neighbouring plants. There are actually two camelias to the left of the exochorda. I cut the right hand one down to about 18 inches a year ago to see what would happen, and it's got loads of new growth. That one should have been moved to a different spot this summer if I hadn't strained my back! Still in the grand plan...

The mahonia is in need of a serious haircut, and I will do that sometime soon.

Working along from the left (beyond what's shown in the photo), there are the following plants in a row in this bed:

Bamboo (regularly thinned)
Hypericum (gets cut right back every winter)
Dogwood (newish, so not quite sure about this one yet)
Rose (due for a hard prune)
Camelias (get pruned and thinned most years)
Exochorda (under consideration)
Mahonia (occasionaly pruned, but getting too big)
Cotinus (occasionaly pruned, but getting too big)
Spirea (gets lightly trimmed, as it doesn't grow that fast)
Hypericum (gets cut right back every winter)
Rose (due for a hard prune)
Choisya (previously pruned hard but needs it again)
Forsythia (got cut almost to the ground this summer)

What I'm considering is hard / rejuvenation pruning everything in this list (e.g. down to ~ 12" or less). It's a bit drastic, but as long as everything survived would, I think, give me better looking plants across the board once they've regrown. I know it's not a long term solution, as there are simply too many large shrubs for the space (I inherited the garden when I moved here), but that's why I'm considering moving some.

Are there any plants in this list I'd be likely to kill by hard pruning?

Getting back to the exochorda, it does produce lots of nice white flowers every year, still, so it's definitely on the 'keep' list, I just want it in a better shape.

Piers.

All those shrubs respond well to renovation pruning, and most can be lifted and moved if you so wish, however a decent grubber would be required to lift them, looking at the picture I would consider moving the Exochorda now whilst it’s dormant, the camellia hard prune in the spring once you have enjoyed its flowering, may take a couple of years to flower better, once you have the desired shape then keep it this way by selective pruning each year, by doing so it will always flower well, mahonia I would do in the spring, you could take all that growth down and they respond very well, average time is about five weeks for bud break, the dogwood if it’s new then trim it down a little in late winter, once established you can renovate these really hard and will send up many coloured stems for the following winter, the continus also responds well to renovation pruning.

Thanks for the advice.

The dogwood is one I transplanted from somewhere else in summer three years ago, so it's reasonably well settled in now. I've been a bit confused by what I've read online about pruning it. Are you supposed to cut it down to the ground annually to get the coloured stems, and when you say 'late winter' do you mean around February time?

In general terms, if I'm not fussed about hanging on till after things have flowered in the spring, is it OK to prune now, or should I wait till the weather starts to warm up again?

For climate info, I'm in SW London.

The cornus family I don’t stool them but cut them back to about a foot from the ground and as a rule I carry this out as you say in Feb, if you do it later then it may bleed when the sap starts to rise in March, when it comes to hard pruning we have to consider nowadays the climate is definitely changing for example yes you could hard prune the camellia now and it should be ok, but it may respond quicker through our now milder winters and then those tender new shoots could be badly burnt or killed off in the event of a severe cold blast so that’s why it would be best done in the spring, apparently we are in for a severe winter late dec through jan, the cotinus can be heavily renovated now, however I do these in mid spring once in full leaf, they respond very well, without jumping on the climate change waggon it is something that we need to be very aware of, and the above advice does take this into respect, I have a clump of Inula that has pushed up and is about to flower now, it died back in early Oct, this climate change I have noted for many years now as most gardeners will be aware of themselves.