Duff had made up his mind, in direct opposition to Carey and other earlier missionaries, that the supremacy of the English language over the vernaculars must be established as a preliminary to the Christianization of India.

He had himself opened in 1830 an English school in Calcutta with an immediate success which had confounded all his opponents.

His authority was great both at home and in India, and was reflected equally in Lord Hardinge's Educational Order of 1844, which threw a large number of posts in the public service open to English-speaking Indians without distinction of race or creed, and in Sir Charles Wood's Educational Despatch of 1854, which resulted in the creation of a Department for Public Instruction, the foundation of the three senior Universities of Calcutta, Madras, and Bombay, the affiliation to them of schools and colleges for purposes of examination, and the inauguration of the "grant-in-aid" system for the encouragement of native educational enterprise by guaranteeing financial support according to a fixed scale to all schools that satisfied certain tests of efficiency in respect of secular instruction.

Duff's influence had assured the supremacy of English in secular education, but he never succeeded in inducing Government to go a step beyond neutrality in regard to religious education, and though the remarkable successes which he had in the meantime achieved, not only as a teacher but as a missionary, amongst the highest classes of Calcutta society no doubt led him to hope that, even without any active co-operation from Government, the spread of English education would in itself involve the spread of both Christian ethics and Christian doctrine, he never ceased to preach the necessity of combining religious and moral with secular education or to prophesy the evils which would ensue from their divorce.
The system inaugurated by the Educational Minute of 1835 and developed in the Educational Orders of 1854 began well.

The number of young Indians who took advantage of it was relatively small.