Missionaries Alice Lan and Betty Hu send a message into Stanley.
A woman comes to their Bethel Mission on a visit. She tells them she'd been used by the British as a warden to take care of 'Japanese prisoners of war' - perhaps supervising Japanese and other Axis civilians who were interned in Stanley Prison on the outbreak of hostilities. Now she is again a warden 'but taking care of the British prisoners in the same camp'.
She agrees to take in messages, so they write down the names of their missionary friends and ask her to find out if they are still alive. They also give her $HK20 for one of them. On March 29 this woman, who they then call "Maria," will return with the news all the friends are alive and with thanks for the money. On May 18 Lan and Hu will see "Maria" searching women passengers at the Star Ferry and surmise she's been transferred because the Japanese suspected her and others of carrying messages.
Source:
Alice Y Lan and Betty Hu, We Flee From Hong Kong, 2000 ed. (1944), 53-54, 57, 61
Note:
It seems that routes for messages into and out of Stanley were established quickly. R. E. Jones records that he wrote to my father, Thomas Edgar, (at that time in the compound of St Paul's Hospital) on February 15, 1942 and he must have sent the letter either with one of the drivers of the Red Cross ambulance or using this kind of 'ad hoc' route: http://gwulo.com/node/9808