The Union Jack
Until the early 17th century and since the 13th century the English flag and jack, used by both merchant and navy ships, had been white with the red cross of St George. The Scottish flag was blue with the white cross of St Andrew. Then, on 12th April 1606 King James I of England and Scotland issued a proclamation :
That from henceforth all our subjects of this Isle and Kingdom of Great Britain, and the members thereof, shall bare in their Maintoppe the Red Crosse, commonly called St George Cross, and the White Cross, commonly called St Andrews Cross, joined together to a form made by our heralds...
This was the birth certificate of what soon became the best-known flag in the world.
Until 1634 the flag was used by both merchant and navy ships, therafter its use was restricted to the kings own ships or ships in the king's immediate service; English merchant ships reverted to flying the St Georges cross and the Scottish ships the St Andrews Cross. At the same time the merchant ensign, red with the St George cross in the canton, came into use and was later legalized in a proclamation of 1674. This proclamation retained the "Flag and Jack White, with a Red Cross (commonly called St Georges Cross)", and repeatedly warned that use of the Union Jack was illegal. Nevertheless, many merchant captains continued to use the "Kings Jack" in order to gain advantages such as better protection, exemption from Port duties in France as well as exemption from the requirement to use a pilot in Holland