The Scottish Saltire and field is one of the key components of the Union Flag. The Union Flag has been used in a variety of forms since 1606, when the flags of the Kingdom of Scotland and Kingdom of England were first merged to symbolise the Union of the Crowns. (The Union of the Crowns having occurred in 1603.) In Scotland, and in particular on Scottish vessels at sea, historical evidence suggests that a separate design of Union Flag was sometimes flown to that used in England. Following the Acts of Union of 1707, which united the Kingdom of Scotland and the Kingdom of England, the standard Union Flag became the national flag of the new United Kingdom of Great Britain. 