<p>A data transfer system comprises a server and a plurality of devices each operable as a client of the server. The server in turn comprises a notification arrangement to notify a device that it is to become a member of a peer group comprising other clients of the server. The server further comprises a client/server data transmitter to send data to the respective device upon such notification. Each device in turn comprises a client/server data receiver to receive respective data from the server, and a peer-to-peer communicator to send respective data received from the server to one or more peers, and to receive from one or more peers respective data that was sent to it or them by the server.</p>
