Gilchrist popularized Hindustani as the language of British administration. When he started as a surgeon with the East India Company's payroll, he was told that Persian was India's main language, but he quickly discovered that none of the people he met spoke either Persian or Arabic very well. His interactions with people helped him to discover that Hindustani was already known to some in the East India Company. They referred to the language as Moors language or simply Jargon, and it was Gilchrist who adopted this as the new language of administration for British India.