Karaway - New Russian/Lithuanian Bread shop in London
Not sure how many of you are near enough to go and buy their bread, but there's a tiny shop in the newly opened Westfield Stratford City that sells good selection of Russian/Lithuanian breads and other baked goodies.
They have Lithuanian style scalded rye, pumpernickel, Borodinsky and several other interesting bread, and they are not mass-produced. I only nibble small pieces of those bread they have for tasting (too much breads at home for consumption...), but they all taste really good. Thoroughly recommend it.