Prior to his postings as an ambassador, he was the high commissioner to Singapore (1981–84) and Tanzania (1984–86) and held the vice-chair of the preparatory committees of United Nations Framework Convention on Climate Change (UNFCCC) and the United Nations Conference on Environment and Development (UNCED), popularly known as the Earth Summit, held in Rio de Janeiro in 1992.
[5] He sat in the International Covenant on Economic, Social and Cultural Rights from January 2007 to December 2010[2] and was a member of the Prime Minister's Council on Climate Change.
[7] While on his assignment with the European Union in Brussels, Dasgupta made frequent visits to London to consult the British archives at the India Office Library.
[10] Dasgupta's conclusions were broadly confirmed by Rakesh Ankit in 2013, based on the newer Dominion Office material made available in 2008–2009.
[11] The Government of India awarded him the third highest civilian honour of the Padma Bhushan, in 2008, for his contributions to Indian civil service.