Some theological scholars believe that Porom Singh was baptized on 3 January 1896. On that date, Pettigrew baptized his first Meitei convert at the watering Morangkhom Hiden Tapham. Porom Singh would have been only about eleven or twelve at the time and it is possible that such a public act would have caused uproar. After his baptism, Porom Singh left Imphal with Pettigrew and functioned as Pettigrew's right-hand man at Ukhrul. In December 1912, he became the headmaster of a school at Ukhrul, where his teaching responsibilities included preaching the gospel. He was one of only seven Christians who stood by Pettigrew. At the outbreak of the First World War, he helped Pettigrew to raise a labour corps, later becoming a corps leader and an interpreter. He received excellent testimonials when he served in France and on his return to India, was exempted from house tax.