olddog has mentioned "The Feather Men" by Ranulph Fiennes, a work of fiction, however, he also wrote "Where Soldiers Fear To Tread" which is an account of his two years as an officer in the Sultan of Oman's army.
This was prior to the coup where the current Sultan overthrew his father and prior to the BATT arrival, probably about 1968-69, and details the rather medieval conditions that prevailed under the old man. The book also describes the military activity in the Dhofar region where much of the communist insurgency was active. I have corresponded with a man who also served there who has cast some doubt on the accuracy of the book but it still remains a favourite.
Sorry for the slight thread drift.