It's a Sorbus seedling, probably Sorbus aucaparia (Rowan or Mountain Ash). It will have been "self-sown" by a bird about two years ago flying past.

Thanks Fractal. Should I keep it? How big and fast does it grow?

It can make a small to moderate sized tree up to 30ft (eventually) though most specimens sit between 15-20ft. It makes a nice tree for moderate gardens and is native and great for wildlife, especially many birds including Thrushes such as Song, Mistle, Blackbird, Redwing and Fieldfare.

If it's in the wrong place, move it in autumn or try Bonsai'ing it (not sure if thats the right wording!)

If you have the space for a small tree then I would recommend keeping it. It has white flowers in spring and then red berries in autumn. If you wish, you can use the berries to make rowan jelly to serve with meat dishes.

Thanks Bulbaholic...I will keep it. I could do with a small tree.

These are not really 'small' trees Macpat, so plant carefully, I get loads of these seedlings in my garden and I confess I pull them out, they come from a huge tree next door and to tell the truth one is enough !

Thanks for the advice Grandmage.........I will have to think about this one.