1. A control system for a vehicle operable to implement a speed control function, the control system comprising: an input for receiving an input of a target speed at which the vehicle is intended to travel; target speed torque determining controller module for determining an instantaneous value of a target speed torque parameter corresponding to an amount of torque that should be developed at a given position in a powertrain in order to control the vehicle to travel at the target speed; a modifier controller module operable to receive the instantaneous value of target speed torque parameter generated by the target speed torque determining controller module and to output to a filter a value of a filter torque parameter, the value of the filter torque parameter being determined in dependence on the value of the target speed torque parameter, a current speed of the vehicle and the target speed of the vehicle, the filter being operable to filter the value of filter torque parameter to generate a value of a filtered torque parameter, the system being operable to command the powertrain to develop an amount of torque corresponding to the value of the filtered torque parameter.