The India Office records are in the British Library, not the UK National Archives. Citations may begin with "IOR" for "India Office Records."
Moir, Martin. A general guide to the India Office Records. London: British Library, 1988. Firestone Library (F) Z6621.I43 M64
India Office Records and Private Papers (British Library guide to the India Office records and related materials)
India Office records
L/P&S/18 (selections): British policy in Asia: India Office memoranda [microform]
Printed guide: DA47.9.I4B74
Consists of memoranda prepared by the Political and Secret Department of the India Office for the information of policy makers. The material is noteworthy in part because it documents the opinions of India Office staff in the field. We have vol. 1: The Middle East 1856-1947.
G/12: East India Company factory records [microform]: sources from the British Library, London
Printed guide: none
Consists of Factory Records of the East India Company from the Oriental and India Office Collections at the British Library. The records document the business activities of the agents and factors of the Company and also provide insight into local matters. See http://www.adam-matthew-publications.co.uk/digital_guides/e.aspx
L/MIL (selections): British military intelligence on China and the Boxer Rising, c. 1880-1930 [microform]: secret gazetteers of the provinces of China, confidential print and intelligence reports
Printed guide: Firestone Microforms Oversize DS764.2 .B75 2004q
Confidential reports and intelligence produced by the British government in India and now part of the India Office records in the British Library. See http://www.idcpublishers.com/ead/374.xml