The system and design issues of a multiband passive radar demonstrator developed by BAE Systems Advanced Technology Centre have been reported [1], together with some initial results from measurement trials. Further enhancements have been implemented at system, hardware and software levels to improve the overall performance of the demonstrator, through the introduction of analogue cancellation circuitry, computer control of RF band selection and switching, and faster run time signal and data processing. This paper briefly summarises the original multiband passive radar demonstrator, then outlines the rationale for the various enhancements, their practical implementation, and the supporting analysis, simulation and modelling. Results from recent trials of the enhanced demonstrator with civil aircraft ‘targets of opportunity’, that confirm the improved detection performance and multiband operation, are presented and discussed.