Which plant is this?

Bluebelltime

bertrand-mabel

Not sure but could it be a walnut? The new leaves look very much like ours at the moment but the older leaves are very glossy.

Borderline

Looks like a young Ash tree, Fraxinus Excelsior.

bertrand-mabel

@Borderline Never thought of Ash. Don't know why not as we have so many around us but it certainly does look like one.

nutcutlet

I'll second Ash Tree

Bluebelltime

Thanks everyone. Not sure how it got there, its growing in pot where im growing a rose 

Borderline

You probably have an Ash tree nearby. In my old garden, I was digging up new plants every year. 

Fairygirl

They seed freely. Can be difficult to get out if you don't notice them. If you want to keep the rose, it's a good idea to remove it as soon as possible.