The incidence of childhood obesity is rising in the United Kingdom and this has far-reaching and serious consequences both for the physical and psychological well-being of the child, as well as significant financial implications for the health service. General practitioners (GPs) play a central role in identifying and assessing such children and directing them to the best services. While most cases of obesity are simply due to an imbalance in calorie intake and expenditure, children do need to be formally assessed to ensure that red flags are not missed, which might signify an important underlying aetiology, co-morbidity or complication. To date, there have not been tools available to guide a GP through this assessment. In this paper, we present and explain the thinking behind a tool, which was developed for use by GPs from Bristolas part of a trial to assess the transferability of a childhood obesity clinic into primary care. We look at the evidence base behind the guidelines and then assess the appropriateness and safety of the 152 referrals made using this tool. We believe that this screening tool would enable over 85% of obese children to seek their initial weight management in primary care. Additional evaluation is needed in different regions to ensure effectiveness, sensitivity and specificity of this new tool.