Can anybody tell me what this is?

[ohfook]

This has grown alarmingly quickly behind my shed this summer. It's about 5ft tall and doesn't appear to be growing from under a fence or anything.

Can anybody tell me what it is? Initially the leaves looked like they were from an apple tree but they've changed and don't anymore if that's any help!

Some kind of willow maybe? We get them popping up from time to time, just pull them out when we notice them. Smaller than yours though!

maybe Dogwood?

Probably a willow. If not then a Prunus, perhaps a sucker from a nearby flowering cherry.

Having enlarged the picture, I’m discounting Prunus. Not dogwood. But one way to confirm a dogwood is: pull a leaf gently apart across the middle, till there’s a 4mm gap. The sap is so sticky that if you hold the leaf up by one end, the other end hangs below it apparently by magic.

Thanks for the suggestions. I've just done the leaf test and it's definitely not dogswood - there was very little sap at all.

Looks like Salix- willow

Think it’s a goat willow. If so, it will grow into a huge plant with invasive roots.

Thank you- I think the it is a goat willow. After a bit of a Google my understanding is that it's good for pollinators but the roots can be a bit of a problem so I think it's going to have to go.

I have one that self seeded in a pot. It's currently got tussock moth caterpillars on ☺️
You could try and transplant if possible?
Keep it well trimmed.

I’ve got two in pots. Most years they give me pussies