Any chance of getting a photo of a leaf or the entire plant?

Maybe a Crapemyrtle. Lagerstroemia

That was my first thought, but in searching for a pic to compare, I'm not sure there are enough sections/calyxes, whatever the proper anatomical term is.

It's many years since I lived in the UK but I don't ever remember seeing a crape myrtle there. Apparently there may be a few now, albeit needing an extra hot UK summer to flower, but I don't think they are very common?

Maybe Exochorda, Pearlbush

I suspect a Hypericum
I crop the image

My sugeestion based on ;
Pods seems to be split into mostly three parts
Calyx remains (in blue) seems papery, thin and flexed backward, some pod lose them.
There are stigma's remains present (in red)
I suspect the withering leaves behind (in green) are part of the plant, if so, it seems consistent to Hypericum

How ever there are many Hypericum species and their pods do varies, some round, some pointy, some very thin. some with prominent calyx, thus species identification from pods will be difficult

If you have any chance to take another visit, also notice whether the plant is a tree, or shrub, how tall?
If you could, take pictures of all plants, remains of leaves (even dried one), stems (whether small stem round vs square), bark, base of plant etc. this will help a lot to suggest or exclude something
Mean while this is a Hypericum seed pod from shutterstock.com

https://www.shutterstock.com/i...

Apologies for the late reply.

I hope this helps..

I went back to the place that I took the photograph but there was now no trace of the bush left, so I'll have to wait until next year..