It depends on the period. In the age of the East India Company most administrators arrived in India without their families, and so most of the cooking was done for them by their Indian servants and mistresses. That means that they would have eaten a lot of the local food, especially high class food as they positioned themselves as at least as important as Indian royalty. There was one key difference, the British loved meat and lots of it. Fowl and mutton was the main meat for the British because beef and pork were hard to get in Muslim and Hindu India. That did not stop them from trying to raise the meat locally, but local objections usually ended that effort.

With steamships making the journey to India much shorter, and a change in the views of race came a change in the British administrators life style. Women now more regularly made the voyage from Britain, and having an Indian mistress became less acceptable. This meant that at important dinners and social events European food was the only acceptable food, and as such a party at an administrators house in India would be much the same as one in England. They did continue to have a lot a meat. According to an article in the Jan. 22 1887 edition of the British Medical Journal "They eat even more meat and a larger number of times, than they do in England.... Each of the principle meals, such as breakfast and dinner, consists very often of three or four heavy dishes - chops, steaks, boiled meat, roast meat, curry, etc."

Indian food continued to be an important part at non-official meals, such as breakfast. Curry dominated these meals, being easy to make and available in a large variety. It is the essential meal of the Raj, eaten by administrators and soldiers all over India for a variety of meals. If you want to see some recopies from the period check out Anglo-Indian Cookery At Home: A Short Treatise For Returned Exiles by Henrietta A. Hervey which was written so that people in England could teach their servants to make meals that their Indian servants make in India.

Sources

“Are Anglo-Indians Gluttons?” The British Medical Journal 1, no. 1360 (1887): 169–169.

Burton, David. The Raj at Table: A Culinary History of the British in India. London ; Boston: Faber, 1993.

Henrietta A. Hervey. Anglo-Indian Cookery at Home : A Short Treatise for Returned Exiles. London : H. Cox, 1895. http://archive.org/details/b28047898.