Membrane computing models (also known as P Systems) that solve optimisation problems using genetic algorithms, ant colony optimisation, quantum-inspired evolutionary algorithm and particle swarm optimisation have been defined and are efficiently used in several applications. This paper describes the design of a variant of the existing Distributed P system (dP system) that is augmented with new features that enable centralised monitoring and communication with all the other components of the distributed system. This proposed model is titled Monitored Distributed P System (MDP System) and its innovative application in performing Cross Layer Optimisation in wireless adhoc networks is also presented. In the proposed MDP System each node in the network is represented by a P system that can independently perform Cross Layer Optimisation using particle swarm optimisation. Discussions on the communication complexity of the proposed model and the experimental results presented are also suggestive of the fact that the proposed Monitored Distributed P System is suitable for real time optimisation in a dynamic and distributed environment.