A Choice Modelling (CM) experiment is developed with the purpose of gaining some insight on how to identify the relevant population for the valuation of an environmental asset. The experiment is based on a survey of Perth residents over the values they attach to Kings Park, the largest urban park in Western Australia, 4/5 of which is native bushland. We design the experiment in order to isolate NUVs form UVs so that trade-offs between attributes of the asset imply tradeoffs between Use Values, Non-Use Values and money. One can then estimate the coefficients for each attribute and analyse the effect of distance on patterns of use. Preliminary results are obtained using data from a pre-survey trial of the questionnaire.