Kammala jumla mai zuwa: Bayan ta dawo Penang daga Ingila a 1927, ta shiga kamfanin lauya na Lim & Lim Advocates da Solicitors. Lokacin da yaki ya barke a 1948 da kuma
Jafananci sun mamaye Malaya, Oon ya gudu ya tafi Singapore. Koyaya, ba da daɗewa ba Singapore ta faɗa cikin mamayar Jafananci kuma, amma yayin da aka ba da izinin 'yancin jama'ar Asiya, Oon ya yanke shawarar yin amfani da wannan' yancin da fasa-kwauri da isar da wasiƙu ga fursunonin yaƙi waɗanda aka tsare a kurkukun Changi.