The British Red Ensign (1707 - 1801) flag is excellent for indoor and outdoor use.
Originally used by English merchant ships at the time when the Kingdom of Scotland united with the Kingdom of England. It consists of the Union Jack in the top left portion of a plain red background. It is still used today by Navy merchant ships and registered civilian vessels.
Ensign - The term used to describe the National (emblem, signal, badge, flag) for sea vessels, to signify heraldry.