Location-based services (LBS) and context-aware systems typically exploit the tracking of people to offer personalised services. Examples of these sorts of applications include allowing vulnerable people to summon help to their current location, providing personalised guidance, ordering a taxi and finding the nearest cash point. To provide such services, information about the users' location needs to be published to one or more service providers (possibly third party organisations.) Key factors in the acceptance of such systems are preservation of control and awareness of dissemination of this information; people using these services do not want to be under surveillance. The fundamental difference between tracking and surveillance is who is in control. There is little or no provision for access control to location information in current systems.