What's the overall size (height and width) of this plant? Is it a shrub or a tree?

I'm not sure if it's classed as a shrub or tree to be honest! At a guess i'd say its a large shrub. It's grown to about 6ft and is about 3ft wide.

Could be Exorchorda macrantha

i think you are correct bamboo. there is a wonderful one in a garden in the main street of the village.

Exochorda macrantha The Bride as suggested.

that's brilliant, thanks everyone!