Pak Pais in Hong Kong

https://en.wiktionary.org/wiki/pak_pai

1977, John Le, The Honourable Schoolboy, Folio Society 2010, p. 471:

He took pak-pais, knowing they were less under the thumb of the police.

John Le Carré’s, The Honourable Schoolboy, is the sentence, “He took pak-pais, knowing they were less under the thumb of the police.” 

xxxx

York Lo: Pak Pai means white plate which is just a regular license plate as in normal cars. Chinese character is 白牌 . Since any car can be a Pak Pai there is no picture of them