I think you would be interested in reading some of the many literary works about India by Rudyard Kipling. He was born in India and wrote many stories and poems about the people and the British soldiers who were stationed there. One collection of his poems which depicts life for a British soldier stationed in colonial India is Kipling's Barrack-Room Ballads (1892). It contains his "Mandalay" and "Gunga Din." One of the best motion pictures ever made is Gunga Din (1939), based very loosely on Kipling's poem. It presents a very vivid picture of the lives of British soldiers in India--uniforms, drilling, military tactics, weaponry, enlisted men's psychology--while telling an exciting story about a native uprising. Naturally Kipling's poems and the Hollywood movie are heavily slanted in favor of British imperialism, but they offer an answer to your question: "How would a British soldier in India be making the world better for his country and also the local people?"