Looks like it could be a tree seedling to me, is the stem woody?

Bay tree seedling ?...give a bit of a leaf a good crush then sniff.

My other thought was some kind of flowering cherry seedling

Thanks. Yes, the stem is quite woody. It definitely wasn't planted deliberately. I will test a leaf and get back to you on that one. ;)

Could it be willow? Does anybody think that damage on the leaf could be vine weevil?

Think most willows are deciduous

Now I feel silly...

Don't Stera… I had decided I could not id!

Update: Hi, thanks everyone. I broke a bit off on of the leaves. The leaves are waxy and quite aromatic. But I don't cook so have no idea what a bay leaf smells like!

it a bay tree alright, crush a few leaves and put in pot when boiling ham or bacon, yum yum

Probably needs moving soon from where it has self seeded then.

Hmmm, it'll be quite big then in time then?
I'm not sure where I'll be able to find room for it, maybe somewhere in the back garden although presumably it'll need quite a big space.

Well a bay tree can grow to over 7 metres but you can also grow in a large container and this will control the trees size.