Union Jack or Union Flag?

When the ‘Union Jack’ was first introduced in 1606, it was known simply as the ‘British flag’ or ‘flag of Britain’ and was ordered to be flown at the main masthead of all ships, warships and merchant ships – English and Scottish.

The name ‘Union’ first appears in 1625. Various theories seek to explain how the flag became known as the ‘Union Jack’, but most of the evidence points towards its derivation from the use of the word ‘jack’ as a diminutive. It was certainly employed before 1600 to describe a small flag flown from the small mast mounted on the bowsprit, and by 1627 it appears that a small version of the Union flag was commonly flown in this position. For some years this flag was called the ‘Jack’, ‘Jack flag’ or ‘King’s Jack’; and by 1674 it was formally termed ‘His Majesty’s Jack’. By then, however, it was also commonly called the Union Jack, and this usage was officially acknowledged.


In the 18th century the small mast on the bowsprit was replaced by staysails on the stays between the bowsprit and the foremast. By this time the Ensign had become the principal naval distinguishing flag, so it became customary to fly the Union Jack only when in harbour, and from the jackstaff – a specially rigged staff in a ship’s bows. Note therefore that the jack flag predated the jackstaff by over 150 years, and its name was related to its size rather than the position in which it was flown.

It is often claimed that the Union Flag should be described as the Union Jack only when flown in the bows of a warship, but this is a relatively recent idea. From early in its life, the Admiralty frequently referred to the flag as the Union Jack, however it was used, and in 1902 an Admiralty Circular announced that Their Lordships had decided that either name could be used officially – a verdict awarded Parliamentary approval in 1908 when it was stated that ‘the Union Jack should be regarded as the National flag’.

Cdr Bruce Nicolls OBE RN (Retd)