The key aim of the PsyGrid project was the creation of an information system to ascertain and characterise a large, representative cohort of schizophrenics, beginning from their first episode of psychosis. The cohort was to be drawn from eight geographically dispersed regions of England, covering in total one-sixth of the entire population. In order to meet the current and future requirements we needed to build a secure distributed system, which not only could support remote data collection, but could also be integrated with other data sets, applications, and workflows for statistical analysis. We concluded that a service-oriented architecture was required and that the implementation technology should be Web services. In this article we present the design, deployment and operation of the PsyGrid data collection system as a case study in applying Web services to health informatics. The major problems we faced were related to the deployment of Web services into an existing network infrastructure, but overall found Web services to be the most suitable middleware technology.