Three years later, in January 1910, Jinnah was elected to the newly-constituted Imperial Legislative Council. All through his parliamentary career, which spanned some four decades, he was probably the most powerful voice in the cause of Indian freedom and Indian rights. Jinnah, who was also the first Indian to pilot a private member's Bill through the Council, soon became a leader of a group inside the legislature. Mr. Montagu (1879-1924), Secretary of State for India, at the close of the First World War, considered Jinnah "perfect mannered, impressive-looking, armed to the teeth with dialectics..."Jinnah, he felt, "is a very clever man, and it is, of course, an outrage that such a man should have no chance of running the affairs of his own country."

For about three decades since his entry into politics in 1906, Jinnah passionately believed in and assiduously worked for Hindu-Muslim unity. Gokhale, the foremost Hindu leader before Gandhi, had once said of him, "He has the true stuff in him and that freedom from all sectarian prejudice which will make him the best ambassador of Hindu-Muslim Unity: And, to be sure, he did become the architect of Hindu-Muslim Unity: he was responsible for the Congress-League Pact of 1916, known popularly as Lucknow Pact- the only pact ever signed between the two political organizations, the Congress and the All-India Muslim League, representing, as they did, the two major communities in the subcontinent."

The Congress-League scheme embodied in this pact was to become the basis for the Montagu-Chemlsford Reforms, also known as the Act of 1919. In retrospect, the Lucknow Pact represented a milestone in the evolution of Indian politics. For one thing, it conceded Muslims the right to separate electorate, reservation of seats in the legislatures and weightage in representation both at the Centre and the minority provinces. Thus, their retention was ensured in the next phase of reforms. For another, it represented a tacit recognition of the All-India Muslim League as the representative organisation of the Muslims, thus strengthening the trend towards Muslim individuality in Indian politics. And to Jinnah goes the credit for all this. Thus, by 1917, Jinnah came to be recognized among both Hindus and Muslims as one of India's most outstanding political leaders. Not only was he prominent in the Congress and the Imperial Legislative Council, he was also the President of the All-India Muslim and that of the Bombay Branch of the Home Rule League. More important, because of his key-role in the Congress-League entente at Lucknow, he was hailed as the ambassador, as well as the embodiment, of Hindu-Muslim unity.