When neighbours urged Lynn Sabberton and her partner, Terry, to flee from their home in Wennington one day in 2022, the couple weren’t sure they should bother. A fire was burning in their village, on the eastern edge of London, but Terry thought it was too far away to be a problem. Struggling with a lung disease made worse by the record 40C heat that day, 19 July, he was wearing only his underwear and refused to budge from his armchair.

Lynn remembers two police officers kicking open their front door and shouting that it was time to go. Lynn pleaded to be allowed to get Terry some clothes and was bundled upstairs to find them. Could she grab some papers? No. Her purse? No. Her cat, Jack? Also no.

As they stumbled out into the unbelievable heat, the sky was dark and there was panic among the crowd of neighbours. No one was remotely prepared for the disaster unfolding around them: a fire that had leapt from a nearby field into the heart of their village. Over the next few hours, 18 of the village’s homes would be burned, including Lynn and Terry’s.

In total, 70 houses were destroyed across the UK that day in a record 600 wildfires – the largest loss of British housing to a threat previously assumed to be more relevant to California or southern Europe, and evidence of the worsening climate crisis.

Wennington’s fire was one of dozens that erupted in a great ring encircling the city, a scenario far beyond anything in the London fire brigade’s (LFB) experience. The brigade, one of the world’s largest, ran out of fire engines, deploying all 142 of them, and the log records incident commanders making desperate appeals for more crews, hoses and water that could not be met.

The heat took a toll on firefighters, their protective suits becoming so sodden with perspiration that they turned wearers into “a boil-in-the-bag meal where you’re literally being cooked”, as one officer described it.

At senior levels, the brigade had realised that higher temperatures caused by the climate crisis would make wildfires more likely and that some would cross the “rural-urban interface” to burn houses. But the unprecedented events of 19 July 2022 showed the scale of the new threat faced by a brigade largely unfamiliar with wildfires.

“We’re London, we’re urban, we don’t do fields,” a senior officer said after the fires. That has since changed and the brigade says it has learned lessons, putting all crews through wildfire training and buying a fleet of all-terrain vehicles and specialist equipment, including giant sprinklers. This alone won’t be enough: the brigade’s commissioner has publicly called for further investment to meet future wildfires.

But there is still a fear of much bigger fires to come. Sami Goldbrom, a London fire brigade group commander who has led research into future threats, said the destruction in July 2022 could very plausibly have been far greater if the winds had been stronger.

“Think of all the houses so close together, we’re so densely populated,” he said. “There’s nothing to say that the fire couldn’t have spread all the way through and where would it stop? And we’ve got terraces, high-rise buildings, all that flammable cladding. It could so easily have been a second Great Fire of London.”

That prospect of a wildfire leaping uncontrolled between buildings, a process that caused widespread devastation in Los Angeles last year, is underlined by new modelling commissioned for my new book, The Response.

Carried out by Dr Tom Smith, an associate professor in environmental geography at the London School of Economics, the research used a Canadian wildfire model known as Prometheus. Smith ran a dozen simulations of a wildfire that hit Dagenham on the day of record heat in July 2022 in which 14 homes were lost. Smith wanted to explore the effect of minor shifts in the wind direction.

In the worst of the simulations, the fire rapidly reached 120 homes, a result that Smith said made “my hair stand on end”.

One challenge for our future resilience is getting recognition for a threat that rarely seems realistic, especially when the weather is cool or wet. Another is that the machinery of government is arguably not geared to provide joined-up thinking.

For example, a significant weakness is that water supplies, including those needed for firefighting, are in private hands. In Wennington, the first crew at the scene was hampered by weak pressure in the mains. When contacted by the LFB, the local water company said the flow had been reduced “to allow them to carry out some testing”.

In response to an environmental information request, Essex & Suffolk Water, the company involved, said the flow to the village was restored, but only at 7pm, six hours after the fires had started. Although privatised water companies have a legal obligation to provide a minimum flow to households, there is no similar requirement to supply fire brigades. Northumbrian Water Group, which owns Essex & Suffolk Water, declined to comment for this article.

Finding out which department is responsible for ensuring firefighters have enough water proved difficult. In England, fire and rescue services come under the Ministry of Housing, Communities and Local Government while wildfire policy is the responsibility of the environment ministry, Defra. After an approach for this article, it was the Environment Agency that responded, saying it was reviewing drought plans “to ensure water companies have worked with their local fire and rescue services to maintain adequate water supplies during fires”.

All this comes as hotter and drier conditions – made more likely by rising global temperatures – mean more wildfires are set to cross the so-called rural-urban interface dividing fields from housing. A study by the Ordnance Survey estimated that as many as 1.8m homes in England are close enough to green spaces to be at risk from wildfires.

There are some solutions. After the fire in Dagenham, the local authority started cutting firebreaks at the edge of open spaces, and last summer one of them saved homes from a huge grass fire. The leader of the local council described the park’s staff as “unsung heroes”.

In Wennington, after months living in temporary housing, Terry’s illness deteriorated and he died. Lynn’s house is being rebuilt but she will be moving in alone.

David Shukman is the BBC’s former science editor. His book, The Response: A Story of Fire and Flood in Britain’s New World of Extremes, is out now.