Definitions for "Blue Peter"
Keywords:  hoisted, flag, peter, foremast, sail
Blue and white flag for the letter "P".
A blue signal flag with white square in the center, hoisted on the foremast to indicate a vessel is ready to sail. It was a recall to the crew "that they repair on board" and for shoresiders to conclude any business they had with the vessel.
A blue flag with an oblong white center, indicating a ship is about to sail when hoisted, at different periods, at the foremast or mainmast. Its name is said to derive from the French verb partir, to leave; or from Sir Peter Parker (1783), Admiral Cornwallis, known as "Billy Blue"; a corruption of "blue pierced"; or from "peter", an old name for a cabin trunk. Take your pick