A monitoring system is disclosed, suitable particularly for a prison or similar environment, comprising a network having at least two computers, one or more condition-sensing and or monitoring devices, the system being arranged to enable any one of the computers to act as a server at any time, comprising a hierarchical list installed on each computer listing the priority by which the computers can become servers and a priority of threads operating on each computer, said priority of threads including a first thread arranged to check whether each other computer is active and a second thread adapted to use the hierarchical list and data determined via the first thread to determine which computer is to be used as a server.