Following the death of his brother he succeeded to the title of 12th Baronet Grant of Dalvey on 11 February 1936.

In 1919, after the Third Anglo-Afghan War, he was the Chief Delegate at the Rawalpindi Conference which ended the British protectorate of Afghanistan.

[3] He served as the Chief Commissioner of the North-West Frontier Province of British India from 1919 until 1921.

He decided to pursue a political career and was chosen as Liberal candidate for Roxburgh and Selkirk where his wife was from.

At the general election held that year, the other parties left the seat for the two Liberal candidates and Grant was narrowly defeated; He did not stand for parliament again.