Wikipedia
The Blue Ensign is a flag, one of several British ensigns, used by certain organisations or territories associated with the United Kingdom. It is used either plain, or defaced with a badge or other emblem.
The evolution of the Blue Ensign followed that of the Union Jack. The ensign originated in the 17th century with the St George's cross (the Flag of England) in the canton, and with a blue field (top right).
The Acts of Union 1707 united England and Wales with Scotland in the Kingdom of Great Britain, thus producing a new Blue Ensign with the new Union Flag in the canton. With the Act of Union 1800, Ireland joined the United Kingdom and St Patrick's Cross was added to the Union Flag and, accordingly, to the cantons of all British ensigns from 1 January 1801.
Ensign of the United Kingdom.svg| The modern Blue Ensign of the United Kingdom | The British Blue Ensign (1707–1801) Blue Ensign 1620.svg| English Blue Ensign as it appeared in the seventeenth century.
Usage examples of "blue ensign".
At first he presumed that such a fine ship must belong to the English East India Company, but her defaced blue ensign showed she was a privately owned vessel, like his own.
From a stripped sapling between the hut that served as a stable and the inn itself flew the blue ensign of Sarronnyn.
Since Biehl has no carriage for hire, not that the firewagon drivers knew, Lorn resumes walking, past the outermost pier, and the brig that bears a dark blue ensign-that of Spidlar, he thinks.
Ah, now they have the blue ensign of old Foxey - Foote, and they are bending it on below this other flag.
The flag was not the blue ensign of the Navy, nor the tricolour of France, nor even the white banner of the exiled French monarchy.
Ahead of him, the massive bulk of the Cumberland, 74, with the blue ensign at the mizen.
The tricolour here was hoisted above a tattered blue ensign, flaunting a petty triumph.
It was as if a prisoner were appealing to them for aid, and the flapping colours, tricolour over blue ensign, told a tragic story.