Introduced by the RAF in 1914, the Brits actually adopted the roundel idea from the French Air Force, whose roundel contained the same colours, but in reverse. At the beginning of the First World War, ground troops apparently had a blanket policy towards aircraft - fire at them all whether or not they're the enemy's! Hence the adoption of a symbol to clearly identify friend from foe.
In popular culture, the roundel is perhaps better known as the logo of British rock band The Who, as well as a symbol of the Mods. British fashion label Ben Sherman has also been known to toy with it. We just love it for its stark simplicity. Look out for one in Talo Luck :)