The Killigrew family were secret backers of piracy in Cornwall. In 1583 a Spanish merchant ship was driven into Falmouth by storms. Lady Killigrew led a boarding party onto the vessel, killing the crew and stealing the cargo. She was sentenced to death for piracy, but was let off.

In the years between 1560 and 1582 Lady Mary Killigrew was a Lady under Queen Elizabeth I. She was the wife of Sir John Killigrew, who was the vice-admiral of Cornwall, England and the royal governor of Pendennis Castle. During that time, piracy was allowed by the authority, as long as it was done quietly and with little bloodshed. Lady Killigrew took up this endeavor with great enthusiasm. She went on many pirating cruises along the English coast.

In 1583 a German merchant ship was driven into Falmouth by storms. Lady Killigrew led a boarding party onto the vessel, killing the crew and stealing the cargo. She herself took up her sword and helped pillage the astonished crew. Her crew rowed away with loot that included jewels, heavy silver and pieces of eight.

Queen Elizabeth I heard about the attack and was very angry. Lady Killigrew was tried, found guilty of piracy and sentenced to be hanged along with her lieutenants. But at the last minute the Queen, who liked Lady Killigrew, relented and this pirate lady was reprieved and given a long jail sentence. Lady Killigrew’s fame as the first English royal pirate was long remembered. She very possibly influenced other women pirates like Mary Read and Anne Bonny.