From Where China Meets India: Burma and the New Crossroads of Asia, by Thant Myint-U (Farrar, Straus and Giroux, 2011), Kindle Loc. 1280-1290:
When the British left Burma in 1948, they left the country in the hands of the men who had been on the extreme fringes of the student nationalist movement just a decade before. They were almost all Buddhists (by background if not practice) and ethnic Burmans. Before the Japanese invasion, they were not particularly important, but the war had radicalized society and they had seized the opportunity, first to collaborate with the Japanese and then to turn against them, in March 1945, just in time to avoid being arrested and hanged as Quislings. They included men like Aung San, father of Aung San Suu Kyi. They were immensely popular and even though they were still in their late twenties and early thirties stood head and shoulders above the older politicians, who were tarred as not having been daring enough. Aung San and many of his colleagues were then gunned down in 1947 in a still puzzling assassination plot, but others from the pool of ex-student radicals formed the first independent government. They would take Burma out of the British Commonwealth and launch the country down what was to be a not very happy path through the rest of the twentieth century.
Some on the British side had been worried about the fate of the Shan and other ethnic minorities in an independent Burma and suggested detaching the upland areas and keeping them as a British crown colony. British frontier officials were particularly fond of the hill peoples, such as the Karen along the Thai border, who had fought consistently and often very courageously against the Japanese.