the computing means is arranged to supply image information to the device onto which an image is projected from the projector;

the plurality of remote signaling devices are operable to transmit signals to a receiver portion of the device onto which an image is projected from the projector only in response to a request signal from the device onto which an image is projected from the projector;

the device onto which an image is projected from the projector includes position indication means for determining the position of the pointing device relative to a surface of the device onto which an image is projected from the projector;

the pointing device is operable to:

take precedence over the remote signaling devices; and

selectively enable each remote signaling device, and

the device onto which an image is projected from the projector is a communication hub of the system, arranged to:

request information from each remote signaling device in turn, by polling;

receive control signals from the pointing device and the plurality of remote signaling devices; and

transmit the control signals from the pointing device and the plurality of remote signaling devices to the computing means on a single communications link, which link is capable of conveying signals both from the pointing device and the remote signaling devices, in order to control an image on the device onto which an image is projected from the projector.