MPS have called for formal guidance to employers on relaxed dress codes and flexible working during heatwaves as the UK prepares for the hottest July day ever recorded.

A group of MPs warned heat-related deaths could treble by the mid-century unless the Government took action to tackle the dangers of soaring summer temperatures.

More than 2,000 people died over 10 days of 2003, when a heatwave pushed temperatures to as much as 38.5C, and the Met Office warns that hot spells of a similar intensity will occur every other year by the 2040s.

In 2015, the UK saw the hottest July day on record, with temperatures hitting 36.7C, but the Met Office predicts highs of up to 37C for tomorrow.

Without the Government developing a strategy to protect vulnerable people, such as the elderly, numbers dying from the heat could rise to 7,000 a year by 2050, a report from the parliamentary Environmental Audit Committee said.

The report is published as the UK swelters in a prolonged heatwave hitting northern Europe, with scientists warning that climate change is making such heat extremes more likely.

The committee’s report calls on the Government to take steps including:

•Ensure NHS England issues guidance to prepare the NHS for more frequent heatwaves, with NHS organisations submitting annual heatwave plans to ensure they are prepared.

•Make sure hospitals and care homes are inspected for their resilience to heatwaves.

Change building regulations to make sure new homes and buildings do not overheat, and bring in stricter water efficiency standards to save water.

•Consult on introducing maximum workplace temperatures, especially for work that involves significant physical effort, while Public Health England should issue formal guidance to employers to relax dress codes and allow flexible working during heatwaves.

•Issue guidance for head teachers about safe temperatures in schools and relaxing school uniform policy during hot weather.

•Review the capacity of local authorities to deliver on climate change protection, require them to report on what they are doing and introduce a green infrastructure target for cities to boost greenery such as trees and parks that can help cool urban areas.

•Assess the heat-related risks on public transport such as trains, which can be disrupted and create sweltering conditions during heatwaves, and potential economic losses.

- Launch a public information campaign on the growing frequency and intensity of heatwaves and run a year-round alert system to warn people about health risks.

Mary Creagh, Labour MP and chairwoman of the Environmental Audit Committee, said the Government needed to do more to warn the public of the health risks of heatwaves.

And she said: “It must change building regulations and planning policies to ensure homes and transport networks are able to deal with extreme heat, and that local authorities and cities have green spaces and heat-resilient infrastructure.”