Following Hong Kong tradition, married women may prepend their husband's surname to their maiden surname — Carrie's husband is Lam Siu-por (
林兆波), her maiden surname is Cheng (
郑). Hence
林郑月娥 /
林郑 in Chinese, 'Lam Cheng' in English. This dual-surname form is a Hong Kong / Macau / Cantonese-diaspora convention rather than mainland practice.
