As part of the preparation for World War II in the United Kingdom the Emergency Medical Services provisions were introduced as soon as war broke out. This gave central government a right of direction over both voluntary and municipal hospitals which it had never before possessed.
It was assumed that there would be a wave of air-raid casualties and so patients were discharged or evacuated in order to make the London hospitals ready. The staff who were evacuated had little to do. Some occupied themselves treating local patients, many of whom had never previously had the benefit of specialist attention. Meanwhile, hospital beds stood empty in central London until limited services were resumed.
The organisation of the Emergency Medical Services was an important factor in the development of the system of organisation of the National Health Service.