There are concerns about cognitively impaired older patients’ experiences of general hospital care. Nottingham University Hospital developed a medical and mental health unit (MMHU) as a demonstration model of best practice dementia care. This thesis describes a controlled clinical trial comparing patients’ experiences of care on the MMHU to standard care wards. Patient experience was measured using the structured non-participant observational tool Dementia Care Mapping. Observations lasted 6 hours during which a score was recorded every five minutes for the patient’s mood and engagement and activity, together with incidents of enhancing and detracting staff behaviours. Noise (alarms, background noise and co-patients calling out) was recorded. 90 (46 MMHU, 44 Standard care) patients were observed between March and December 2011. At admission, most characteristics of patients on MMHU and standard care were similar. However, patients observed on MMHU had more behaviour disturbance, more often were care home residents and were less disabled than those observed on standard care. Patients on MMHU experienced a median 11% (95% Confidence Interval (CI) 2%, 20%) improvement in the proportion of time in positive mood and engagement (79% versus 68%); a median 3 (95%CI 1, 5) more enhancers (4 versus 1); a median 13% (95%CI -17%, -7%) less time noise could be heard (79% versus 92%) but a median 15% (95%CI 1, 23%) increase in proportion of time co-patients called out (21% versus 6%). Patients on MMHU had a better experience of care than those on standard care wards in terms of their mood and engagement, number of enhancers and improved noise levels, but experienced more co-patients calling out. This is the first study measuring an intervention to improve cognitively impaired older patients’ experiences in the general hospital and the first study to use the Dementia Care Mapping tool to evaluate an intervention in this setting.