The spatial pattern of summertime ozone concentrations across the British Isles has been revealed using a simple long-range transport model (ELMO). The model describes the chemical development of air parcels reaching an array of 3064 arrival points after 4 days of travel across Europe during typical summertime photochemical episodic conditions. Model results have been compared against observations and the model responses to VOC and NOx controls against established indicator ratios. The model has been used to assess the likely impacts of policy commitments under the Gothenburg Protocol to the United Nations Convention on Long-Range Transboundary Air Pollution and other policy instruments.