This article describes the methodology and observational data from a project that sought to, first, investigate the prevalence of alcohol related harm and alcohol misuse in Cardiff's night-time economy and, second, deliver a targeted server training intervention to premises identified as at risk of misselling alcohol. The bulk of the work is centred on a novel breathalyser survey of drinkers conducted on one Saturday and one Friday each month for 12 months. Due to its novelty in a UK context and the potential value of objective alcohol misuse data, the survey provided important insights into appropriate methodologies for surveying night time economies as well as unique insights into the nature of alcohol misuse.