On the eve of Indian Independence, as Britain prepared to devolve the Crown’s treaties with Tibet to the Indian government, the Tibetan government was debating its future treaty relationship with India under the 1914 Simla Convention and associated Indo-Tibetan Trade Regulations. Soon after Indian independence, Tibetan government made an expansive demand for return of Tibetan territory along the McMahon Line and beyond. This led to a long diplomatic exchange between Lhasa, New Delhi and London as India deliberated its response to the Tibetan demand. This article decodes the voluminous correspondence between February 1947 and January 1948 that flowed between the British/Indian Mission in Lhasa, the Political Officer in Sikkim, External Affairs Ministry in Delhi and the Foreign Office in London, on the Simla Convention and the ensuing Tibetan territorial demand. Housed at the National Archives in New Delhi, this declassified confidential communication provides crucial context for newly independent Indian state’s relationship with Tibet. It also reveals the intricacies of Tibetan elite politics that affected decision-making in Lhasa translating to a fragmented and often contradictory policy in forging its new relationship with India. Most importantly, this Tibetan territorial demand undermined the diplomatic efficacy of Tibet’s 1947 Trade Mission to India entangling its outcome with the resolution of this issue. This was a lost opportunity for both India and Tibet in building an agreement on the frontier which worked to their mutual disadvantage in the future. © 2021 Indian Council of World Affairs.