This grower is sure of this plant identification.
Plant is 'Dark Beauty' - cultivar reputedly becomes more blue in deeper shade. Plants were divided this April and potted up as they were growing too prolifically!
Japanese toad lily, Toad lily
Tricyrtis formosana (Japanese toad lily). This is an upright plant which will grow to 60-90cm. The flowers are spurred heavily spotted, purplish pink and have a yellow tinged throat, they are produced in terminal cymes in early autumn. The glossy dark green leaves clasp the stems.
They are fully to frost-hardy plants in partial-shade in humus-rich, moist soil, You can propagate from seeds in the autumn or by division in spring.
Italics = data drawn from parent genus or speciesView Full Plant Finder Record