In this paper, we develop a decentralised controller for large-scale linear interconnected dynamical systems by using, for each subsystem, a low-order model for the interactions. The output of the interaction model is improved online using a model-following technique. The controller gains are calculated only once, and they are easy to compute since all operations are done subsystem by subsystem. A sufficient condition is also developed for the stability of the global system with the decentralised control subject to structural perturbations. It is seen that satisfaction of this condition provides a robust design which is insensitive to structural perturbations.