An agricultural tractor (10) control system comprising an electronic control unit (ECU) (16) is provided in addition to a method of controlling a tractor (10). The ECU (16) is arranged to receive in real time signals from a plurality of sensors (40, 42) associated with operating functions of the tractor. The ECU (16) is also arranged to output control signals to a plurality of controlled operating components. Macroinstructions, or macros, are inputted to the ECU (16) by a user by direct definition or Internet download for example. Each macro comprises a condition and a command. The condition includes a trigger value and a corresponding input variable sensed by a respective sensor (40, 42, 50). The command involves the transmission of one of said output control signals to control an operating component in a predetermined manner. The ECU (16) is operable to run said macro during which the command is executed in response to the condition being met.