What island is part of the Islands of Furness and has a castle that was used as a base by the Yorkist pretender Lambert Simnel in 1487?
Piel Island: Piel Island lies half a mile (1 km) off the southern tip of the Furness Peninsula in the administrative county of Cumbria, though historically within Lancashire north of the sands. Piel Island:  It is one of the Islands of Furness.
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