Unmanned and autonomous systems have a key role to play in delivering future maritime capability, where this requires an appropriate command and control (C2) architecture to operate a heterogeneous mix of unmanned systems. The UK has made significant progress over the last 5 years in developing such an information architecture known as MAPLE (Maritime Autonomous PLatform Exploitation), as a result the integration of new unmanned systems into MAPLE has become relatively straightforward. The programme has seen its architecture iteratively developed and tested, both in live and synthetic events, most recently in Australia in late 2018 as part of a 5 eyes Autonomy Strategic Challenge. As the fourth phase of MAPLE comes to a conclusion, this paper will underline the progress that has been made in prototyping a solution that has successfully achieved stressing goals around planning, tasking, in mission control and exploitation of multiple heterogeneous unmanned systems. The paper will explore how Phase 4 has also leveraged its open architecture approach and wider research and development into manned-unmanned teaming and automated policy management, giving end users more flexibility and control in terms of vehicle tasking, whilst building overall system trust. As part of this wider focus, Phase 4 has featured an integral focus on concept development, human factors and the non-functional aspects, notably security and safety, all key to the eventual fielding of a MAPLE like capability. The paper will set out specific achievements in these areas and highlights from the final MAPLE 4 demonstrations in May 2019, set out thinking on the next phase, towards implementation, and conclude with a look at a number of MAPLE spin-out projects.