Enchanter's nightshade maybe? Bit hard to tell, with no flowers present and not being able to see the basal leaves...

looks like chickweed to me. Remove it before it sets seeds. it is an annual so if removed before seeding it shouldn't be a problem next time.

thank you both for your answers.

Cickweed has ordinary fibrous looking roots and Enchanters Nightshade has thicker white ones and spreads with enthusiasm. Can't see how it could get nto a hanging basket it you used new compost though.

I used 50 50 new and home made, probably came from the home made.

definitely not enchanters nightshade. leaf shape and arrangement is wrong. I have lots if it in the shade in the back garden.

seed in your home made compost will be the source.

Thank you all for your comments.

Anyway its nice and easy to pull out...