The increasing growth in the application of global computing and pervasive systems has necessitated careful consideration of security issues. In particular, there has been a growth in the use of electronic communities, in which there exist many relationships between different entities. Such relationships require establishing trust between entities and a great deal of effort has been expended in developing accurate and reliable models of trust in such multi-client environments. Many of these models are complex and not necessarily guaranteed to give accurate trust predictions. In this paper we present a review of some of these models before proposing a simple, lightweight model for trust. The proposed model does not require the estimation of a large parameter set, nor make great assumptions about the parameters that affect trust.