Here’s another recipe from Daniel Leader’s Living Bread, that features buckwheat flour. In the book the recipe is called Pain au Sarassin Avec Miel, Pavot et Tournesol.
My version uses smaller proportion of buckwheat flour to wheat flour than the original. Also I added a small amount of celery seed for flavor.
Cat's Pajamas 
What a beautiful bread! Buckwheat is so underrated and underused, but adds such a delightful flavor.