Tiny flowers

I think this is a kind of verbena but am not sure. It's being used as a hedge at the end of a garden that backs onto the field and provides good seclusion as it is a good 6/7 feet tall. I love the delicacy of the little flower clusters.
Today has been rather dull and overcast. We have, so far, missed the snow but did have some sleety rain this morning. Bit of a breeze as well so photo not as sharp as I would have liked. Temperature set to drop to -4 tonight.