These are some abstracts from "The Book of Flags" -- Vice-Admiral Gordon Campbell, V.C., D.S.O, and I.O. Evans, F.R.G.S. -- Third Edition -- Oxford University Press -- London -- 1957.
The designs on flags were chosen not at random but because of their meaning. Some were deliberately selected in recent times; others have been in use from time immemorial, their origin coming from ancient legends or being completely lost in the past. To interpret the meaning of a flag helps us to understand and appreciate something of the history and ideals of the country which flies it. [page xi]
Whether a flag conforms to the heraldic rules or not, it needs to be easily distinguishable from others and have a striking design. Words are seldom used on flags; they are difficult to read when waving in the breeze or sagging during a lull, and even when legible they are neither impressive nor heraldic. Small details of design are equally hard to distinguish: bold patterns of contrasting colour are most easily recognisable. [page 4]
The recent war produced two new ensigns of unusual pattern.[...]That of the National Fire Service also had its Ensign with the Union Flag in the canton; its second and third quarters were blue and its fourth quarter red. These, however were land flags; boats belonging tothe Fire Service wore the Blue Ensign which shows they were Government vessels, with the N.F.S. badge in the fly. [page 50].
Each of the six states in the Australian Commonwealth has its own badge, which appears in a circle in the fly of its ensign. [...] That of Western Australia greatly astonished the naturalists when it was discovered: it is the famous black swan (it is now shown as swimming towards the hoist).[pages 56-58]