Datapoint Chinese Pidgin English/Proportion of native speakers

Goldmann (1899: 151) states that the children of foreigners in Shanghai were looked after by Chinese amahs who spoke Pidgin English, which is therefore "the first language which the children learnt".
Hall (1944: 95) states that one of his informants, Mrs. Helen Groff-Smith, "learned C[hinese] P[idgin English] as first language", apparently in similar circumstances.
It is likely that such children had multilingual childhoods: Willens (2010: 91), who grew up in Shanghai in the 1930s, recalls switching from Pidgin English to Russian at age 4.