That's a holly sapling, just ordinary, common holly (Ilex aquifolium). I find them all the time, they drive me mad, it'll probably be a seed dropped by birds that's germinated - but where there's one, there's usually more dotted about.

Since they get 12metres high by 4-8 metres wide, it needs a lot of space - it might berry on its own anyway, if there's other holly trees in the vicinity, depends if its male or female, which you can't tell unless you see berries or closely inspect the flowers.

Likely still several years away from flowering, though. This fall, I would transplant it to a spot with more room to grow, though.

.Thinking of putting it in a large tub,as is squashed in a little corner under a bush.Can I do that now , I am in the UK so into Spring or have to wait until Autumn?

Advise is much appreciated ,Thank You

Do it now and keep it well watered - waiting just means the roots will get much deeper...

I should have thought of that, Bamboo, Solada! We're already well into early summer, here, so I automatically think "this fall" when talking of transplanting.

I'd have agreed with you Tug, except its being transplanted to a container - much easier to keep watered.