I've always called it Green Alkanet, looked up Pentaglottis sempervirens - same thing!
Good Luck removing the offending plant. Apologies, still chuckling. It is such a pretty blue.
So unless your happy to dig half way to Australia and three feet around I suggest a little Glyphosate.
"You don't stop gardening because you get old, you get old because you stop gardening." - The Hampshire Hog