The Commonwealth is an unusual place to study flags, because so many of its members had to design one while carrying the marks of the same former ruler. Some kept the Union Jack. Some dropped it. The reds of the Union Jack and the sun on Antigua and Barbuda's flag are answers to the same question, given about two centuries apart.
What flags do for a country
A flag is a claim of sovereignty and a piece of everyday shorthand at once. In diplomacy it works as a unifying image; in a former colony it can also work as a statement that the colonial period is over. Which of those two jobs a flag does depends less on the design than on who is looking at it.
Colors and their conventional readings
The colors are not chosen at random, and the conventions are fairly stable: red for bravery or valor, blue for peace or the sea, green for fertility or the land. Recurring devices carry more specific baggage. The Union Jack in a canton says something about shared history whether or not the country still wants to say it, and stars usually point outward, to navigation or to aspiration.
Cultural influence works in both directions. Indigenous symbols and colonial markers often sit on the same flag, which is an accurate picture of the history even when it is an uncomfortable one.
Two examples
Antigua and Barbuda
The Flag of Antigua and Barbuda
View Flag →A sun motif over black, blue and white: African lineage, the Caribbean sea, and hope for the future. The sun does most of the work, and the design has nothing carried over from the colonial period.
Australia
The Flag of Australia
View Flag →The Union Jack and the Southern Cross on one field. One half of the flag records where the state came from, the other half records where it is. Australians have been arguing about the balance for a long time.
How Commonwealth flags evolved
The pattern across the Commonwealth runs from colonial ensign to independent emblem, but it is not a clean break. Colonial devices survive on plenty of flags, sometimes because a country is comfortable with them and sometimes because changing a flag is politically expensive. What changed everywhere is who decides.
Vexillology and public feeling
Vexillologists read the symbolism and the design history, but they also read the reaction. How a population treats its flag, whether it is flown casually, guarded jealously, or argued over, tells you as much as the colors do.
Where the designs are going
Design trends move, and so does the pressure for flags to represent more of the people living under them. Globalization pulls national symbols toward a shared visual language, and the Commonwealth's flags will keep negotiating between that and whatever they were originally for.