A modular lighting controller system for controlling luminaires, the system comprising: a marshalling device which comprises an input port , at least one output port and at least one connection port , wherein the input port is connectable to said at least one output port and to said at least one connection port ; an extension device which comprises at least one output port, a further connection port and a mating connector connectable to the at least one connection port of the marshalling device; and a control device which comprises at least one mating connector, wherein, in use, the extension device is connectable to the marshalling device through interconnection of the connection port of the marshalling device and the mating connector of the extension device such that the at least one output port of the extension device is connectable to the input port of the marshalling device , wherein, in use, the control device is connectable either to the marshalling device directly through interconnection of the mating connector of the control device with the connection port of the marshalling device or, when the extension device is connected to the marshalling device, through interconnection of the mating connector of the control device with the further connection port of the extension device, such that the control device controls the flow of power from the input port to at least one outlet port , wherein the input port has a plurality of electrical connections including a live connection , a neutral connection , an earth connection , a switched live connection and a permanent live connection , wherein each connection port has a corresponding plurality of electrical connections including a live connection , a neutral connection , an earth connection , a switched live connection and a permanent live connection , and wherein each output port is adapted to connect to a luminaire connector . a marshalling device which comprises an input port , at least one output port and at least one connection port , wherein the input port is connectable to said at least one output port and to said at least one connection port ; an extension device which comprises at least one output port, a further connection port and a mating connector connectable to the at least one connection port of the marshalling device; and a control device which comprises at least one mating connector, wherein, in use, the extension device is connectable to the marshalling device through interconnection of the connection port of the marshalling device and the mating connector of the extension device such that the at least one output port of the extension device is connectable to the input port of the marshalling device , wherein, in use, the control device is connectable either to the marshalling device directly through interconnection of the mating connector of the control device with the connection port of the marshalling device or, when the extension device is connected to the marshalling device, through interconnection of the mating connector of the control device with the further connection port of the extension device, such that the control device controls the flow of power from the input port to at least one outlet port , wherein the input port has a plurality of electrical connections including a live connection , a neutral connection , an earth connection , a switched live connection and a permanent live connection , wherein each connection port has a corresponding plurality of electrical connections including a live connection , a neutral connection , an earth connection , a switched live connection and a permanent live connection , and wherein each output port is adapted to connect to a luminaire connector . <EOS>