This is an oval, second early which was probably bred in the Shetland Isles in late Victorian times. It has a very dark blue netted skin with pale yellow flesh and a purple vascular ring. Its relative earliness and its shallow eyes along with its oval shape indicate that it has some "North American" genes in its background breeding. Many in Shetland would like to think it was rescued from an Armada wreck in 1588. This is unlikely but there are some round late maincrops with deep eyes and the classic purple ring from that geographical area and it is just possible that a parent of the current Shetland Black is a better candidate for the legend.
The current version is wonderful crofter fuel with large yields of small/ medium tasty, floury tubers produced under a profusion of short, dark, wind-resistant stems. They are wonderful cooked whole and served with real mutton. Children should be blindfolded as most find the colour "gross".
I helped launch this one as first a microplant, then a minituber but it seems to have become established recently as a certified field crop in a small but stable way and it seems pointless not to offer it now as a normal seed potato.