OBJECTIVE: To explore why patients with cancer treated by London hospitals report worse experiences of care compared with those treated in other English regions. DESIGN: Secondary analysis of the 2011/2012 National Cancer Patient Experience Survey (n=69 086). SETTING AND PARTICIPANTS: Patients with cancer treated by the English National Health Service (NHS) hospitals. MAIN OUTCOME MEASURES: 64 patient experience measures covering all aspects of cancer care (pre-diagnosis to discharge). METHODS: Using mixed effects logistic regression, we explored whether poorer scores in London hospitals could be explained by patient case-mix (age, gender, ethnicity and cancer type). Because patients referred to tertiary centres and/or with complex medical problems may report more critical experiences, we also explored whether the experiences reported in London may reflect higher concentration of teaching hospitals in the capital. Finally, using the data from the (general) Adult Inpatients Survey, we explored whether the extent of poorer experience reported by London patients was similar for respondents to either survey. RESULTS: For 52/64 questions, there was evidence of poorer experience in London, with the percentage of patients reporting a positive experience being lower compared with the rest of England by a median of 3.7% (IQR 2.5-5.4%). After case-mix adjustment there was still evidence for worse experience in London for 45/64 question [corrected]. In addition, adjusting for teaching hospital status made trivial difference to the case-mix-adjusted findings. There was evidence that London versus rest-of-England differences were greater for patients with cancer compared with (general) hospital inpatients for 10 of 16 questions in both the Cancer Patient Experience and the Adult Inpatients Surveys. CONCLUSIONS: Patients with cancer treated by London hospitals report worse care experiences and by and large these differences are not explained by patient case-mix or teaching hospital status. Efforts to improve care in London should aim to meet patient expectations and improve care quality.