[15] Wylie records that he was "connected with the London Mission as a printer, almost from its first establishment",[7] but he passes unmentioned in Robert Morrison's journals of his early years in Macao and Guangzhou (then romanized as "Canton").
[5][16] Wat was noted by the Chinese Recorder as having received his initial Christian instruction not from Morrison but from William Milne,[8] which would have occurred after he had (illegally) left Guangdong for Malacca around 1815.
[13] In Malacca, he worked for Milne at the Anglo-Chinese College along with Liang Fa,[6] who instructed him in the art of printing[8][14] and successfully converted him to belief in Christianity.
[5] There are unclear references to some long-standing dispute between Wat and Liang that was eventually resolved;[20] they worked together in Malacca and again to continue the mission with another native worker[n 2] after Morrison's death in 1834.
[22] In the early 1830s,[23] Morrison's son John trained Wat to use the mission's recently imported Albion press and in the art of lithography,[19] which reduced the effort, time, and expense of printing.
[19] His son Ahe was tricked into leaving Morrison's house and arrested in the street; as the boy proved a ready informant, he was kept a long time but treated well.
[28] When James Legge moved from Malacca to Hong Kong in 1843[n 3] to supervise the establishment of its new theological seminary,[29] Wat accompanied him, along with He Futang[n 4] and He Yasan.
[29] In 1853, during the early stages of the Taipings' victories in central China, Legge sent Wat and Wu Wenxiu[n 6] to Shanghai to negotiate with them for the entrance of Protestant missionaries to occupied Nanjing.
[13] In addition to the works by Morrison, Milne, Liang, and others that Wat assisted with editing and printing, he was directly responsible for various Chinese-language tracts.