This grower is sure of this plant identification.
I have just potted up two of these which had self seeded. So they will need to bee kept in the pots for a while
Dracunculus vulgaris (Dragon arum). A native of the Mediterranean region. Grows to about 2m. The large leaves are red-veined and deeply divided. In late spring, a thick stem bears one or more large spathes, up to 35cm tall, like that of the arum lily, green on the outside and red to purple or black on the inside, with a purple to black spadix. Emits a potent, foul odour which attracts flies for pollinating.
They are frost hardy. They will need a sunny position with well drained soil that dries out in the summer. In severe winters protect dormant tubers with a cloche or dead bracken.
Grown for their distinct spathes.