The well-known Snakeshead Fritillary. Slender stems bearing narrow, grey-green leaves carry large, bell-shaped flowers with square shoulders, varying in colour from white through pink to dark brooding purple, marked with distinctive chequering.
Think this is almost certainly what I bought at Beetham in spring 2015 to put in a small turquoise pot. The flowers are slightly bluer purple than suggested here. Planted out autumn 2016 in spring bed.
Garden Astilbe are a popular choice for shady gardens, where they perform well if given a rich, moist soil and regular watering. This midsized selection has fluffy plumes in a bright-pink shade, over a mound of ele.