Being able to make timely contact with an expert who is willing and able to answer the problem at hand is important. However finding such an expert using the systems found in many organisations can be difficult because experts are too busy to ensure information is complete and up to date. We have designed, implemented and evaluated a prototype Expert Recommender Systems based on an investigation of the requirements for such a system in two knowledge intensive organizations together with review of the literature and comparison with existing systems. We designed a triangulated approach which combines automated expert profile creation and maintenance, validation by the expert, and feedback on the expert and the system by the searching party. In this paper we present results from a usability study we conducted of the prototype system with a particular focus on the searching algorithm we designed.