This is less of a question than more of a "tell me everything you know" about colonial Burma. What was it about colonial rule that alienated Burma against joining the Commonwealth?
Burma was an old regional military power with a strong sense of cultural superiority and the British colonization was felt as a severe humiliation reinforced by British insensitivity towards Buddhism (such as British civil servants and officers not taking of their shoes in temples) and,
more importantly, some basic decisions by the colonizers that favoured "inferior" people over the Burmans:
a) The British relied on the non-Burmese (ie non-Burman) hill tribes and other ethnic minorities as soldiers, those were people the Burmans had treated as serfs (and in some cases as actual slaves) add to this that the Burmans had a great warrior tradition and considered themselves a martial people and you get a lot of resentment over this.
b) Colonial Burma also saw massive Indian immigration in the interwar period - the well educated among them got civil service jobs ahead of Burmans and they dominated trade (in competion with the Chinese), and since the Burmans traditionally looked down on Indians this was also felt as a great humiliation.
Burma was the major land theatre of WW2 in Asia with 60% of all Japanese casualties and the Burmese nationalists under Aung San (father of famous Suu Kyi) supported the Japanese until January 1945, while the hill tribes and other minorities (notably Kachins and Karens) fought for the allies. The British commanders of the guerilla forces in Northern Burma made promises to, among others, the Kachins of autonomy, but the Attlee government chose to accept Burmese independence without any real guarantees for the rights of ethnic minorities who had fought bravely for the allies (after giving up on India the British lost all interest in Burma).
Burma then descended into civil war between the ethnic minorities, who almost overran Rangoon, and the Burman government, this civil war - with the addition of Chinese backed communists and exiled KMT soldiers - continued well into the 90s (and legacies of it in some forms even today). Basically Burmese nationalism was anti-British to a much greater extent than other Asian nationalisms - even long before the xenophobic Ne Win coup in 1962.
