The 2017 World Workshop Classification system for periodontal and peri-implant diseases and conditions was developed in order to accommodate advances in knowledge derived from both biological and clinical research, that have emerged since the 1999 International Classification of Periodontal Diseases. Importantly, it defines clinical health for the first time, and distinguishes an intact and a reduced periodontium throughout. The term ‘aggressive periodontitis’ was removed, creating a staging and grading system for periodontitis that is based primarily upon attachment and bone loss and classifies the disease into four stages based on severity (I, II, III or IV) and three grades based on disease susceptibility (A, B or C). The British Society of Periodontology (BSP) convened an implementation group to develop guidance on how the new classification system should be implemented in clinical practice. A particular focus was to describe how the new classification system integrates with established diagnostic parameters and pathways, such as the basic periodontal examination (BPE). This implementation plan focuses on clinical practice; for research, readers are advised to follow the international classification system. In this paper we describe a diagnostic pathway for plaque-induced periodontal diseases that is consistent with established guidance and accommodates the novel 2017 classification system, as recommended by the BSP implementation group. Subsequent case reports will provide examples of the application of this guidance in clinical practice.