Rangoon was re-captured by Patriotic Burmese Forces and Allied Force on 2nd May 1945. Sir Dorman – Smith returned as Governor and Lord Mountbatten of Burma handed over the State Power on 16th October 1945. Sir Dorman – Smith formed Governor's Executive Council on 1st November 1945. Sir Paw Tun became the Chief of Governor's Executive Council. 34 M.Ps were nominated by the Governor for legislative body on 31st December 1945.
On 28th February 1946, the first legislative meeting was held in Council Chamber.
On 21st March 1946, Thakin Tu Oak accused Bogyoke Aung San of murder and urged legislature to put him on trial for committing crime.
On 26th September 1946, Bogyoke Aung San joined the Governor Council and became the Deputy Chairman. Then he formed the interim National Government.
Red Flag Communist Party member Daw Saw Mya and Ye Ne San Nyunt Led 200 Indian Labors to go on strike picketing the Secretariat on 15th January 1947. Bogyoke Aung San and Executive Council members invited native Karen Leaders to the Secretariat and asked for their opinions.
General election to form the basis of a Constituent Assembly was held on 9th April 1947. Candidates from the Anti-Fascist People's Freedom League (AFPFL) won 248 seats out of 255. (Other candidates in the election included a few independents and communists). It was overwhelming victory. Bogyoke Aung San and Executive Council members invited native Shan and Karanee Leaders to the Secretariat and made discussion with them.
The first stride of Constituent Assembly in Council Chamber began on 10th June 1947.
On 16th June 1947, Bogyoke Aung San submitted 7 policy guidelines to draft the constitution. His proposal was strongly supported by 16 legislators. Bogyoke Aung San's proposal was approved by constituent Assembly on 17th June 1947.Bogyoke Aung San delivered a speech entitled 'under No one's Rule' to the Assembly. A draft constitution committee consisted of 55 members was approved by the Assembly.
On 20th June 1947, the first meeting of draft Constitution Committee was held. Sao Shwe Thaik, Saopha of Nyaung Shwe, became the Chairman of the Committee.
On 19th July 1947, Bogyoke Aung San and Six of his Cabinet Ministers were assassinated in the Executive meeting hall of the Secretariat Building. A cabinet secretary and a bodyguard were also killed.
Sao Shwe Thaik, Saopha (Saw Bwar) of, was elected as the Speaker by the second constituent Assembly on 29th July 1947. On 15th September 1947, Sao Shwe Thaik and U Chan Htun, the responsible person to re-draft Constitution, bowed low to Martyrs’ stone-pillar before they went into the Council Chamber.
The third Constituent Assembly was called on 15th September 1947.
On 24th September 1947, U Chan Htun's version of the Union Constitution was promulgated by third Constituent Assembly. Sao Shwe Thaik was appointed as the President (Temp) of the Union and U Nu was elected as the Prime Minister (Temp) on 25th September 1947.
U Nu nominated his Cabinet and it was approved by the Constituent Assembly on 3rd January 1947. On 4th January 1947, Union Jack Flag was lower from the pole fronting the Council chamber and Flag of Union of Burma was raised for the Declaration of the Independence from UK at 4:20 AM. In Council Chamber, the ceremony representing the smooth handover of Power from the Governor to U Nu's Cabinet was held at 4:45 AM. Constituent Assembly became the interim Parliament.