There were two main ways for Artemius Holmes to come into contact with Arsenio Leblanc. The consistent way was a pre-scheduled meeting once or twice a week, depending on how busy either were. The method to contact Mattheus for his appearance as a consultant on a case was a bit roundabout but usually got to his ears within half an hour.
It was through the network of street rats that Liam had been a part of and seemed to have grown. Artemius would either fetch one of them to pass on the message or he would call a number of one of the new telephone boxes which someone manned—usually informed by someone part of the network that Brunilda created of which number to call as it changed frequently.