Its a spurge, aka Euphorbia lsthyris. If you want to remove it be careful if you break a stem - they exude a milky white sap which is quite caustic so don't get any on your finger and then wipe your eye...

Typo there, its Euphorbia lathyris.. just in case you wanted to look it up!

Lol, how clumsy can you get.....

I thought it very pretty. I've never seen one before, so am glad you put it on. I might try to get one! :) Karen Thanks for the ID Stera!

Wouldn't advise it Karen, unless you want a lot...remember the white caustic sap if you do get one but I have never seen them at garden centres as they are classed as weeds by most people.

What a pity...I like Euphorbia. We have a weedy one here, but its very small and delicate. The sap doesn't bother me at all, but thanks for the warning :)