The Union Flag vs. The Union Jack
In an argument almost as old as the flag itself, the British public have been asking “Is it the Union Jack, or the Union Flag?”
Finally, after much research on the topic, the Flag Institute of the UK have published a report, and their view.
The document, “Union Flag or Union Jack?” is a 12 page summary looking at the question itself, the historical sources and references of both flag names, how each came into being, and thankfully, a conclusion that may once and for all answer the question.