Reliable decentralised stabilisation is considered for general multi-channel plants, where the objective is to maintain stability of the closed-loop system when all of decentralised controllers work together and when one of the controllers is extracted due to a failure. For this control problem, a design method is presented, where a dilated LMI technique is employed for deriving reliable state feedback design, while a version of unknown disturbance observer is used as a decentralised observer for extending the design to output feedback case. Applicability of the proposed method is demonstrated through a power system example, where a model reduction and a low pass filter are further employed.