Lees was for some years principal of the Calcutta Madrasa, where he was also professor of law, logic, literature, and mathematics. He was secretary to Fort William College, Persian translator to the government, and government examiner in Arabic, Persian, and Urdu for all branches of the service; and for some years part proprietor of the Times of India. In 1857 Trinity College, Dublin conferred on him the honorary degree of LL.D., and he was also a Ph.D. of Berlin.