Professor Dame Sally Davies, chief medical officer, urged authorities to get ready as she warned that the 2003 heatwave, which saw temperatures rocket to more than 38C, would be “normal” by 2040.

“As a result of climate change we are increasingly likely to experience extreme summer temperatures that may be harmful to health,” she said.

She added: “We want to make sure that everyone takes simple precautions to stay healthy during periods of hot weather and when in the sun."

Dr Angie Bone, head of extreme events at PHE’s Centre for Radiation, Chemical and Environmental Hazards, reminded Britons that exposure to excessive heat can kill.

She said: “While hot weather is enjoyable for most people and uncomfortable for some, sadly experience tells us that exposure to excessive heat can kill, with most cases of illness and death caused by heart and lung disease.

“Because we are not used to these very hot temperatures in England, it is important that local plans are in place to reduce the impact of harm from very hot weather.

“The Heatwave Plan for England, which is a joint PHE, NHS England, Met Office and Local Government Association publication, exists to provide advice and guidance to healthcare professionals and the public on the effects heat can have on health.”