Solved Request for help identifying plant growing in hedge

I found this plant growing up through a rather sparse Thuja hedge (clay soil, Oxfordshire). It was about 3m tall. At first I assumed it was a juvenile ash (there's a lot about here), but when I cut through the stem (about 2cm diameter), it was fairly soft and hollow centred. There were about six or so stems growing together. The leaves wilted after being cut. Sorry I don't have a picture of the plant in situ, it was only after I'd cut it out of the hedge I thought: I wonder what that was? Photo of a section of stem and leaves attached. Thanks in advance for any suggestions, and apologies if it's completely obvious!

 

Looks like an elderberry.

Blackstart

 

Excellent - many thanks for the quick and helpful reply