The present paper attempted to augment our understanding of the economic thought of 'Grand Old Man of India' Naoroji who was a brilliant analyst of the colonial economy and came up with the principle of economic drain in ‘Poverty and Un-British Rule in India’. The paper analysed his economic thoughts on poverty, estimation of national income, and economic analysis of the drain. The article evaluates Naoroji's 'drain theory' of British imperialism in light of his first attempt to formulate a comprehensive economic critique of the Empire. The paper found that the economic ideas of Naoroji are moulded by the reality of that time and his use of data and statistics to bring home the conclusions is worthy of emulation by young economists. At some point, his analysis may be lacking sound and now established economic reasoning but with his analytical ability, he was able to show the real causes of poverty in India and provided a tool to nationalists who used it for the demand for home rule and independence from the British Empire.