The M. Harriet was the ship from the "On Melancholy Hill" music video that had been destroyed from a pirate attack. Noodle was on board fighting the pirates until she managed to escape an explosion from a bomb and swam over to the lifeboat out in the distance.
It can also be found stored away in the hangar section of the Gorillaz mobile app, accessible through Noodle's racing helmet in the beginning camera section of the app.
