Despite patient preference and many known benefits, continuity of care is in decline in general practice. The most common method of measuring continuity is the Usual Provider of Care (UPC) index. This requires a number of appointments per patient and a relatively long timeframe for accuracy, reducing its applicability for day-to-day performance management. To describe the St Leonard's Index of Continuity of Care (SLICC) for measuring GP continuity regularly, and demonstrate how it has been used in service in general practice. Analysis of appointment audit data from 2016-2017 in a general practice with 8823-9409 patients and seven part-time partners, in Exeter, UK. The percentage of face-to-face appointments for patients on each doctor's list, with the patient's personal doctor (the SLICC), was calculated monthly. The SLICC for different demographic groupings of patients (for example, sex and frequency of attendance) was compared. The UPC index over the 2 years was also calculated, allowing comparisons between indices. In the 2-year study period, there were 35 622 GP face-to-face appointments; 1.96 per patient per year. Overall, 51.7% (95% confidence interval = 51.2 to 52.2) of GP appointments were with the patients' personal doctor. Patients aged ≥65 years had a higher level of continuity with 64.9% of appointments being with their personal doctor. The mean whole-practice UPC score was 0.61 (standard deviation 0.23), with 'usual provider' being the personal GP for 52.8% and a trainee or locum for 8.1% of patients. This method could provide working GPs with a simple way to track continuity of care and inform practice management and decision making.