Pentaglottis sempervirens

UPDATE: ID solved by DavidD ... it's a green alkanet :) 

Can anyone identify this little flower? It's on a plant that I would normally classify as a weed – largely because I don't know what it is! The plant itself is about 18 inches tall and a bit nettle-like, with a ridiculously hairy stem! We have loads of them along one side of our garden, which we normally leave to its own devices apart from a quick mow or two later in the year. It attracts loads of insects.

I'd love to know what it is, so I can add it to my list. Thanks in advance :)