During the EU DEMO Pre-Concept Design Phase, the remote maintenance team developed maintenance strategies and systems to meet the evolving plant maintenance requirements. These were constrained by the proposed tokamak architecture and the challenging environments but considered a range of port layouts and handling system designs. The design-driving requirements were to have short maintenance durations and to demonstrate power plant relevant technologies. Work concentrated on the in-vessel maintenance systems, where the design constraints are the most challenging and the potential impact on the plant design is highest. A robust blanket handling system design was not identified during the Pre-Concept Design Phase. Novel enabling technologies were identified and, where these were critical to the maintenance strategy and not being pursued elsewhere, proof-of-principle designs were developed and tested. Technology development focused on pipe joining systems such as laser bore cutting and welding, pipe alignment, and on the control systems for handling massive blankets. Maintenance studies were also conducted on the ex-vessel plant to identify the additional transport volumes required to support the plant layout. The strategic implications of using vessel casks, and of using containment cells with cell casks, was explored. This was motivated by the costs associated with the storage of casks, one of several ex-vessel systems that can drive the overall plant layout. This paper introduces the remote maintenance system designs, describes the main developments and achievements, and presents conclusions, lessons learned and recommendations for future work.