1. A computerised trading system for trading instruments between trading parties, comprising: a communications network for transmitting electronic messages; a plurality of trader order input devices connected to the communications network, each for generating electronic orders including bid and/or offer orders and for communication to traders of order information received from other input devices over the network; at least one broker order input device connected to the communications networks for generating electronic orders including bid and/or offer orders on behalf of a selected one of a plurality of client traders and for communication to a broker of order information received from other input devices over the network; at least one matching engine connected to the network for matching bid and offer orders input into the system from the order input devices and for executing deals where prices are matched; and a market distributor connected to the network for distributing order price messages to the order input devices, the market distributor being responsible to the order messages and the matching engine.