This paper presents the modelling and parameter estimation of a novel low-cost active hydraulically interconnected suspension through experimentation. The estimated model, combined with a half-car model in state-space, is employed to derive a H∞ control strategy for vehicle body roll control and verified in numerical tests. As an attempt to make the active suspension more affordable, the paper presents a safety-orientated, low cost hydraulic active suspension with interconnected circuits, through which the four hydraulic actuators are controlled by only one pressure valve, which significantly reduced the initial cost comparing to conventional active suspensions with independently controlled actuators. The pressure control unit, as the vital part of the active suspension, is designed, implemented and assembled onto the test vehicle with the existing cylinders and hydraulic piping. An appropriate model and parameters of this pressure unit is essential for model-based optimal controller, since it has to be simple enough for the controller design and also capture the system dynamic characteristics. The empirical approach used for derive the model is presented, and the estimated model matches the test data well in the Bode graph. The derived H∞ controller based on the half-car model and the active suspension model is then verified by a numerical example. Discussions and suggestions for future work conclude the paper.