A very comprehensive directory compiled from the Civil Lists of the Government of India. Includes lists of military officers, recipients of medals and awards and details of those involved in the government of the Sub-Continent.
There is also a fascinating section featuring the fundamental rules of the Civil Service, this gives details such as rates of pay, and pensions given according to length of service.
The real gem, however, is The Record of Services. This is a 437 page section with details of people and their service record in India. For example:
BLAKE, Reginald Gilbert, India Office (executive officer, accnt, -gen's dept.) (b. 20th Feb 1898). - Apptd. asst. clerk, 3rd Dec., 1919, after previous service from 22nd Oct., 1915; second class clerk, 29th April, 1920; exec. officer, April, 1922.
This shows that Reginald was born in 1898 and in 1920, aged 22, he achieved the rank of executive officer. He remained in that position until at least 1933, the date of the publication of this book.
Interestingly this section also includes people who had been retired for many years. Such as John Mitchell Holms, who arrived in India 26th November 1883. The fashion in these times dictated that young 'gentlemen' went to India at the age of about 21, so this man would probably have been born in the early 1860's. He occupied the post of Lieutenant Governor of United Provinces between February and June 1917 and retired in 1919 (possibly about 60 years of age), fourteen years before this book was published.
