Flowers are the wrong type for Honesty. That has ones with four petals in a cross shape. This looks more like a member of the mint family, say Stachys macrantha? That is a wild guess though.
I think it might be this in the link Toni what do you think http://www.google.co.uk/imgres?imgurl=h ... 5&ct=image
I was just looking at that same site before I posted. The only problem is the leaves on it are long and skinny and on yours they are rounder. :?: The leaves of this one, the one Palustris mentioned are more like yours tho.... http://www.mobot.org/gardeninghelp/plan ... ?code=F700