This grower is sure of this plant identification.
Ledebouria socialis (Silver squill). An upright evergreen perennial clump from South Africa. Bears lance-shaped, grey-green leaves and purple-green flowers.
They need gritty, well-drained soil, with a position in the full sun. You can propagate from seeds or by division of established clumps.
Grown for its flowers and makes good pot plants in cool greenhouses.