On the 194th birth anniversary of Dadabhai Naoroji, popularly known as the Grand Old Man of India, Lok Sabha Speaker Om Birla, today paid tribute to the leader. In his tweet, he described Naoroji as an ardent patriot, economic thinker and among the greatest socio-political reformers of India. <br />''<br />''Born in 1825, Dadabhai Naoroji is regarded as one of the most important Indians during the Independence Movement. Naoroji, propounded the 'drain of wealth' theory in his book 'Poverty and Un-British Rule in India'. This theory revealed the loot by the Britishers during the colonial era. <br />