However, some experts are sceptical and believe that technical and regulatory barriers will delay their widespread introduction for years.

The widespread introduction of mayors could also encourage government to decentralise power, it says.

Some groups, such as those with long-term chest disease, appear to do better than others, but as a rule the widespread introduction of the jab has proved disappointing.

However, merchant shipping losses were high until the widespread introduction of convoys in 1917.

The teaching of library hand declined after the widespread introduction of the typewriter in the early 20th century.