English primary care faces a reduction in GP supply and increased demand. To explore trends in GP working time and supply, accounting for factors influencing demand for services. Retrospective observational study in English primary care between 2015 and 2022. Trends in median GP contracted time commitment were calculated using annual workforce datasets. Three measures of demand were calculated at practice-level: numbers of patients; numbers of older patients (≥65 years); and numbers of chronic conditions using 21 Quality and Outcomes Framework disease registers. Multi-level Poisson models were used to assess associations between GP supply and practice demand, adjusted for deprivation, region, and year. Between 2015 and 2022, the median full-time equivalent (FTE) of a fully qualified GP decreased from 0.80 to 0.69. There was a 9% increase in registered population per GP FTE (incidence rate ratio [IRR] = 1.09; 95% confidence interval [CI] = 1.05 to 1.14). This increase was steeper using numbers of chronic conditions (32%, IRR = 1.32; 95% CI = 1.26 to 1.38). Practices in the most deprived decile had 17% more patients (IRR = 1.17; 95% CI = 1.08 to 1.27) and 19% more chronic conditions (IRR = 1.19; 95% CI = 1.06 to 1.33) per GP FTE, compared with the least deprived decile. These disparities persisted over time. All regions reported more chronic conditions per GP FTE than London. Population demand per GP has increased, particularly in terms of chronic conditions. This increase is driven by several factors, including a reduction in GP contracted time commitments. Persistent deprivation gradients in GP supply highlight the need to recruit and retain GPs more equitably.