OBJECTIVE: To investigate variations in quality of acute stroke care and outcomes by day and time of admission in London hyperacute stroke units compared with the rest of England. DESIGN: Prospective cohort study using anonymised patient-level data from the Sentinel Stroke National Audit Programme. SETTING: Acute stroke services in London hyperacute stroke units and the rest of England. PARTICIPANTS: 68 239 patients with a primary diagnosis of stroke admitted between January and December 2014. INTERVENTIONS: Hub-and-spoke model for care of suspected acute stroke patients in London with performance standards designed to deliver uniform access to high-quality hyperacute stroke unit care across the week. MAIN OUTCOME MEASURES: 16 indicators of quality of acute stroke care, mortality at 3 days after admission to the hospital, disability at the end of the inpatient spell, length of stay. RESULTS: There was no variation in quality of care by day and time of admission to the hospital across the week in terms of stroke nursing assessment, brain scanning and thrombolysis in London hyperacute stroke units, nor was there variation in 3-day mortality or disability at hospital discharge (all p values>0.05). Other quality of care measures significantly varied by day and time of admission across the week in London (all p values<0.01). In the rest of England there was variation in all measures by day and time of admission across the week (all p values<0.01), except for mortality at 3 days (p value>0.05). CONCLUSIONS: The London hyperacute stroke unit model achieved performance standards for 'front door' stroke care across the week. The same benefits were not achieved by other models of care in the rest of England. There was no weekend effect for mortality in London or the rest of the England. Other aspects of care were not constant across the week in London hyperacute stroke units, indicating some performance standards were perceived to be more important than others.