ITV News Correspondent Sejal Karia reports on the individuals who lost everything amid the wildfires

The outbreak of hundreds of fires amid record temperatures has been labelled a “wake-up call” on climate change, as the UK counts the cost of the heatwave.

As temperatures climbed above 40C for the first time ever on Tuesday, major fire incidents were declared in London, Norfolk, Suffolk, Lincolnshire, Leicestershire and South Yorkshire amid the tinder-dry conditions.

Tuesday was the busiest day for London Fire Brigade (LFB) since the Second World War, with the service experiencing more than seven times the usual volume of calls, said London Mayor Sadiq Khan.

Although it is understood there were no deaths, London's mayor said 41 homes and warehouses were destroyed throughout the capital. Residents told ITV News the incident was their "worst nightmare".

LFB Assistant Commissioner Jonathan Smith said: “Yesterday’s fires are another example of how we are increasingly being challenged by new extremes of weather as our climate changes, and we’re developing long-term strategies to deal with more incidents like this in the future.”

Several significant fires happened in the capital, while two “large-scale” incidents took place in Upminster and the village of Wennington, east London.

Aerial footage shows fire destroying properties in Wennington, London, as temperatures soared during the heatwave

Bosses at West Yorkshire Fire and Rescue Service, which came close to calling a major incident, warned the situation across the country on Tuesday would not be a one-off and the UK needed to “get prepared”. Deputy Chief Fire Officer Dave Walton said: “Yesterday was a game changer and took us to a completely new level. Fires were spreading much more quickly than ever before.” He said that usually when a big fire happened, it was possible to call on neighbouring services to help, but on Tuesday “everyone was busy and completely stacked out”. “The predictions are we will get heatwaves like this much more regularly, even as much as every three years, due to climate change...we need to see this as a wake-up call."

'I ran as fast as I could with the flames behind me': Wennington resident Steve Rolton describes the moment he fled from a wildfire

In South Yorkshire, donations have started to flood in to support residents who were seen desperately throwing buckets of water on a huge blaze that ripped through a street in Barnsley , destroying six homes.

South Yorkshire Fire and Rescue said it is carrying out investigations into the Barnsley fire, as well as blazes that gutted homes in Doncaster and Rotherham on Tuesday.

Meanwhile, its crews have continued to attend incidents on Wednesday afternoon, including a blaze at a derelict ski village in Sheffield, which has left a plume of smoke over the city.

Two South Yorkshire firefighters were hospitalised amid Tuesday's blazes. Two of their LFB counterparts were admitted to hospital, while 16 in the capital suffered heat-related injuries.

Among those left homeless by Tuesday's wildfires are a pensioner who'd lived in the same place for 60 years and a Norfolk widower whose photographs of his late wife were destroyed .

A "devastated" Keith Gant told ITV News Anglia he now only has the tattoo on his arm to remember his wife by.

Chief Secretary to the Treasury Simon Clarke promised the government will “step in” to help families hit by the fires - though he did not say specifically what help it might provide to those without insurance, whose homes or belongings were destroyed.

London Ambulance Service said it had taken the equivalent of a call every 13 seconds during the two days of extreme heat, with a 10-fold increase in incidents related to heat exposure compared with last week, and an 8% increase in people fainting. NHS bosses have warned that the health service’s “crumbling” buildings are not fit to adapt to the heatwave, which saw hospitals forced to scale back the number of planned operations, install cooling units and try to cool down IT server rooms.

Sangita Lal reports from Sheffield, where there was another fire on Wednesday

A spokesperson for Guy’s and St Thomas’ NHS Foundation Trust said it had experienced significant disruption of its IT systems due to Tuesday’s heat, which meant it had been forced to postpone some operations and appointments.

Nine people have died since Saturday in swimming accidents amid the heatwave and there has been widespread disruption to train services.

The Met Office said 34 observation sites across England provisionally broke the previous all-time record, ranging from Bramham, in West Yorkshire, to Charlwood, in Surrey, while a further five had equalled it on Tuesday.

Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know

A total of six sites, mostly in Greater London, saw temperatures reach or exceed 40C.

Scotland experienced its hottest day on record, with the temperature reaching 34.8C in Charterhall in the Scottish Borders, Met Office provisional figures showed.

Heatwaves are being made more intense, frequent and longer by climate change, and scientists said it would be “virtually impossible” for the UK to have experienced temperatures reaching 40C without human-driven global warming.

Aerial shots display the aftermath of the Barnsley wildfire

There is potentially no respite from the extreme weather, with a yellow warning for thunderstorms in place across a large swathe of England from noon to 10pm on Wednesday.

The Met Office said that while many places will only see relatively small amounts of rain, some slow-moving torrential downpours are possible.

Where these occur there could be 20-30mm (0.8-1.1 inches) of rain in an hour and in some spots 50mm (2 inches) in three hours.