There was a gradual increase in cold-related mortality and emergency admissions after temperatures had dropped below relatively moderate thresholds (from 4°C in East England to 8°C in the South West). There was a 3.8% increase in deaths for every 1°C drop in temperature. • While the adverse effects of winter weather are widespread among the population, different groups are vulnerable according to the type of winter weather conditions being experienced. While older people are the most susceptible to low temperatures, they appear to be less vulnerable during periods of heavy snowfall compared with people of working age who had the highest relative increase in A&E visits. The Cold Weather Alerts should make a distinction between these different types of weather conditions, and target advice accordingly. • Days of extreme cold temperature were only responsible for a small portion of all excess winter deaths because of the relative infrequency of very cold days. This suggests that more emphasis could be given to the lower Cold Weather Alert levels 0 and 1 in order to have a greater impact on reducing the health-related burden of cold weather. • The adverse effects of cold weather may not be immediately apparent and may be delayed by several days or weeks following initial exposure, so short-term forecasts may be less important than the level of care provided by health services over a longer period after a cold spell. • Health and social care managers were positive about the CWP and the alert service, and felt the CWP prompted providers to be more proactive in their response to cold weather and to encourage better joint working across agencies. However, there was a general view that implementation would be more effective if it was led by public health managers rather than emergency planners. • Among frontline staff, there was much greater awareness of the CWP among nurses working in community health services than among those working in primary care. It was also more difficult to engage primary care staff in recognising the health risks of cold weather and taking appropriate action. • Both managers and frontline staff recognised the difficulties of identifying potentially at-risk individuals who were not already in contact with adult social services, suggesting that other ways of identifying such people need to be developed. • Interviews with people who were vulnerable to the effects of cold weather showed that they listened to weather forecasts and developed their own strategies for keeping warm. But none of them received any help or advice specifically related to cold weather from primary or community caregivers, suggesting that many at-risk individuals are missed by the CWP. Resources should be targeted at those who live in cold homes who are socially isolated. • Mathematical modelling showed that the CWP is cost-effective under some scenarios at the high end of the willingness to pay threshold used by NICE, but this estimate is sensitive to the extent of implementation of the CWP at local level. Using sensitivity analysis it is shown that the incremental cost-effectiveness ratio varies from £29,754 to £75,875 per Quality Adjusted Life Year (QALY) gained