Payments for Ecosystems Services (PES) schemes are an underdeveloped component of the policy mix for catchment management in many countries. The importance of intermediaries to such schemes is acknowledged in the literature but few studies go beyond theory to evaluate practice. This paper analyses generic intermediary functions for PES. It then evaluates an innovative example from southwest England that provides illustrations, and some lessons regarding necessary capabilities and characteristics for intermediaries, and understanding of their form, functions and modalities. project was co-developed by a private water company and an environmental charity. The former translated effective demand from shareholders and water customers for improved raw water quality into finance, whilst the latter had capabilities for catchment-scale on-farm delivery and trusted acceptance as an intermediary. While any sector can potentially provide a PES intermediary, the value driven, not-for-profit and politically neutral voluntary sector proves to be a good fit. Such 'boundary organisations' are also well placed for horizontal coordination of catchment management authorities and actions.