A system for monitoring and controlling a fluid flow network having a plurality of flow control valves, each operable manually by a key engageable with a valve spindle, the system comprising: a central database recording for each valve in the network the location of the valve, and the number of rotations of the valve spindle between fully open and fully closed; a key for operating the valves; and a mobile communications device comprising a transmitter/receiver for transmitting data to the central database and for receiving data from the central database • a processor controlled by a software program to o communicate with the central database and to receive therefrom characteristics for the valve at the transmitted position, o characterised in that • the key is a removable key, • the database additionally stores an optimum rotation speed profile for opening and closing the valve, • the mobile communications device is associated with the key and comprises orientation means responsive to rotation of the valve spindle, and • the processor is additionally programmed to receive signals from the orientation means when the communications device is mounted on the key and to calculate therefrom the instantaneous rotational speed of the valve spindle and the amount of rotation of the valve spindle, and control rotation of the valve spindle in accordance with the optimum speed profile included in the received characteristics. a central database recording for each valve in the network the location of the valve, and the number of rotations of the valve spindle between fully open and fully closed; a key for operating the valves; and a mobile communications device comprising a transmitter/receiver for transmitting data to the central database and for receiving data from the central database • a processor controlled by a software program to o communicate with the central database and to receive therefrom characteristics for the valve at the transmitted position, o characterised in that • the key is a removable key, • the database additionally stores an optimum rotation speed profile for opening and closing the valve, • the mobile communications device is associated with the key and comprises orientation means responsive to rotation of the valve spindle, and • the processor is additionally programmed to receive signals from the orientation means when the communications device is mounted on the key and to calculate therefrom the instantaneous rotational speed of the valve spindle and the amount of rotation of the valve spindle, and control rotation of the valve spindle in accordance with the optimum speed profile included in the received characteristics. • a processor controlled by a software program to o communicate with the central database and to receive therefrom characteristics for the valve at the transmitted position, o characterised in that • the key is a removable key, • the database additionally stores an optimum rotation speed profile for opening and closing the valve, • the mobile communications device is associated with the key and comprises orientation means responsive to rotation of the valve spindle, and • the processor is additionally programmed to receive signals from the orientation means when the communications device is mounted on the key and to calculate therefrom the instantaneous rotational speed of the valve spindle and the amount of rotation of the valve spindle, and control rotation of the valve spindle in accordance with the optimum speed profile included in the received characteristics. o communicate with the central database and to receive therefrom characteristics for the valve at the transmitted position, o characterised in that • the key is a removable key, • the database additionally stores an optimum rotation speed profile for opening and closing the valve, • the mobile communications device is associated with the key and comprises orientation means responsive to rotation of the valve spindle, and • the processor is additionally programmed to receive signals from the orientation means when the communications device is mounted on the key and to calculate therefrom the instantaneous rotational speed of the valve spindle and the amount of rotation of the valve spindle, and control rotation of the valve spindle in accordance with the optimum speed profile included in the received characteristics. • the key is a removable key, • the database additionally stores an optimum rotation speed profile for opening and closing the valve, • the mobile communications device is associated with the key and comprises orientation means responsive to rotation of the valve spindle, and • the processor is additionally programmed to receive signals from the orientation means when the communications device is mounted on the key and to calculate therefrom the instantaneous rotational speed of the valve spindle and the amount of rotation of the valve spindle, and control rotation of the valve spindle in accordance with the optimum speed profile included in the received characteristics.