AIMS: The aim of this study was to identify the number of ambulant children with cerebral palsy (CP) who are eligible for single-event multilevel surgery (SEMLS) in the UK, to explore regional variations in care and estimate the outcomes over a two-year period. METHODS: This was a prospective, comprehensive cohort study, to evaluate current surgical practice in ambulant patients with bilateral CP. The case mix, intervention variables, and clinical outcomes, including patient-based outcomes, were recorded in a consented sub-group. Data from children who did not undergo surgery within the time of the study were used for comparison. RESULTS: A total of 203 children were enrolled, over a period of 52 months. There were 138 males and 65 females, with a mean age of 12.6 years (5.4 to 18.1). A total of 188 children met the inclusion criteria. At the time of enrolment, the surgical and non-surgical groups had similar clinical characteristics. Of the 139 children who underwent SEMLS, the mean was 5.3 procedures (2 to 12) per patient. There was considerable variation in the procedures undertaken at the different sites. Outcome measures were available in a subgroup of children. Complications were recorded in 25 children (18%). At two years following SEMLS, the Gait Profile Score improved beyond the minimal clinically important difference, as did the parental perception of motor function (Gait Outcomes Assessment List questionnaire). There was some indication of improvement in motor function (Functional Mobility Scale). While the non-surgical group was small, there was a general decline in gait over the same period in this group. CONCLUSION: National data illustrating the practice of SEMLS across the UK, which is useful for clinicians to inform discussions with patients, were collected in this study. While the natural history of these children is of gradual functional decline, there was a clear signal of the effectiveness of SEMLS. Consensus to standardize clinical practice is needed, as are further studies to assess the outcomes accurately.