Identify this plant please

[CrochetMadRosie]

Can anyone help identify what this is growing in my garden please?
Hampshire, England

It's growing in our hedge which has a mix of old hedge plants and trees in, and seems to be coming from near the base of a viburnum that we planted to fill a gap, but the leaves are completely different.
It's over 6 foot tall now and I'm wondering whether to leave it or take it out.
Thanks!

It looks like guelder rose - viburnum opulus. Which IME is a lovely thing. I don't know if viburnums are ever grafted, if so maybe it's the rootstock of the one you planted.

Or it may be one of the 'old hedge plants' - it'd certainly be at home there.

Thank you.
I will leave it alone then and enjoy the addition to the garden!
It's growing so quickly that I was worried it was going to take over.
Thanks again.

It can take heavy pruning

@MereDintofPandiculation That's useful to know. Thank you!