Hemlock?

This plant has shot up and flowered opposite the dog bin. I rushed to the wild flower identification literature and to my surprise the closest match I could find was Hemlock. (It loooks a bit like Cow Parsley too). Surely some mistake! I am not a botanist and if I have made a mistake, which is more than likely, I would love to know. In any event, early February is very early for any of the potential candidates to be flowering.