Understanding the attitudes of members of the public towards the impact on their privacy of surveillance technologies used to enhance public security is an essential, but complex, consideration for policy makers, where public trust plays a central role. One way of understanding public attitudes is via the assessment of public opinion surveys. However, to ensure that public attitudes are appropriately being measured across all four concepts (privacy, security, trust and surveillance) it is necessary to consider how existing surveys conceptualise and operationalise these terms. This article undertakes precisely this consideration, in order to evaluate existing practices and provide recommendations for future public opinion surveys on surveillance technologies or practices intended to provide security, but which may impact privacy. We have found three issues relating to past approaches: past surveys do not always adequately define or conceptualise the terms they are employing. Second, surveys sometimes rely on the use of examples in lieu of definitions. Finally, and most importantly, we find that existing surveys do not always adequately examine the impact of the public's trust towards the use of surveillance technologies to enhance security, but which may affect their privacy.