plant identifictaion?

Have uploaded a photo into the general gardening photo album...can anyone tell me what it is please as it is growing like mad in my son's garden.   It has tall rhubarb like stems with blue bell like flowers with a deper blue/purple splodge in the centre. The leaves are fairly big with pointy bits...can't remeber the technical term!!

manyt hanks for solving this mystery..have searched the net but can't find a decent plant ident site

I know it is small, sorry, Picture was taken  with my mobile phone...just can't see it properly. have seen the plant before but have no idea what the name is.