London's fire service had its busiest day since World War Two dealing with several blazes in record-breaking temperatures on Tuesday, London Mayor Sadiq Khan has said.

The capital was one of 15 areas around the UK to declare a major incident.

The fires started on a day which saw a record temperature of 40.3C (104.5F) in Coningsby, Lincolnshire.

The forecast is still warm but cooler on Wednesday but there are warnings in place for thunderstorms.

A yellow warning has been issued by the Met Office for heavy showers and thunderstorms which could bring disruption in eastern and south-east England this afternoon.

Despite the fall in temperatures the weather is continuing to affect transport and Network Rail has advised passengers to only travel if necessary - with no direct trains between London and Scotland.

Mr Khan said London Fire Brigade (LFB) received 2,600 calls as it dealt with multiple fires. He earlier told Sky News 41 properties were destroyed in London on Tuesday.

In Wennington, east London, 100 firefighters tackled a blaze which destroyed several homes.

LFB said two rows of terraced houses, four other homes, 12 stables and five cars were destroyed by the blaze, while one firefighter at the scene described it as "absolute hell".

Dramatic images from the scene showed smoke billowing from a number of buildings, some with their roofs collapsed, and extensive damage to the surrounding land.

Speaking to BBC Radio 4's Today programme, Mr Khan said: "Yesterday was the busiest day for the fire service in London since the Second World War.

"Normally we get 350 calls a day, on a busy day we can get up to 500 calls. Yesterday the fire service had more than 2,600 calls a day."

LFB assistant commissioner Jonathan Smith said the brigade dealt with 15 major fires, along with a large number of wildfires and grassland fires.

The service will investigate all those incidents to get a full picture of why the fires occurred, he said.

The heat and dry conditions had created "the perfect scenario" for fires to spread rapidly across grassland and woodland, he said, adding "it was the speed of these fires which was a particular challenge for us to deal with".

Elsewhere in the UK, a number of homes were destroyed by fire in Norfolk, while major incidents were also declared in places including Leicestershire, Hertfordshire, Suffolk, Lincolnshire and Yorkshire.

At Prime Minister's Questions, Boris Johnson thanked firefighters and said he had spoken with the chair of the National Fire Chiefs Council.

LFB said 16 firefighters had heat-related injuries - two of whom were taken to hospital but have since been discharged. South Yorkshire Fire and Rescue said four from their crews had been taken to hospital but have made a full recovery.

Speaking after PMQs, Cabinet Office minister Kit Malthouse told MPs some of the pressure would now ease as the "fiercest heat has subsided" but he warned the summer was likely to bring further hot weather and the risk of wildfire remained elevated.

"That is why we are treating this heatwave as an exacting test of our national resilience and contingency planning," he said.

Tim Stock alerted the fire brigade when he saw flames near his home in Wennington.

Mr Stock, whose house was destroyed, told BBC Radio 5 Live he and his son had spotted the fire in his neighbour's garden but, despite their best efforts with a hose and watering can, had been unable to stop it spreading.

"I reckon about 15 to 20 houses might be gone or uninhabitable," he said.

"My house is completely gone, as is the next door neighbour's and three or four other houses along that bit."

The Fire Brigades Union (FBU) has accused government spending cuts of hampering the ability of fire services to react.

Matt Wrack, FBU general secretary, said: "Firefighters are at the forefront of the climate emergency.

"The demands of the job are increasing but our resources have been under attack by government cuts for over a decade - 11,500 firefighter jobs have been slashed since 2010."

Speaking about the LFB, Mr Khan said he inherited closed fire stations, cancelled engines and firefighters losing jobs when he took over as mayor from Boris Johnson, his predecessor.

He said he has been rebuilding the capital's fire service with kit and more firefighters.

Phil Garrigan, who leads the National Resilience group for the National Fire Chiefs Council, said the UK must now consider what equipment it had to fight wildfires.

He said most European countries where significant wildfires occur have planes or helicopters which can collect or distribute water to areas where fire is developing.

Currently, the UK relied on third parties to provide that capability, he said.

Meanwhile Just Stop Oil demonstrators climbed motorway signs on the M25, near Cobham, Surrey, to protest at the extreme temperatures in the UK.

Police closed sections of the motorway and National Highways said at one stage there was five miles of queuing traffic approaching junction 30 in Essex.

The latest Met Office provisional figures show that Scotland's record-breaking highest temperature, hit on Tuesday, was higher than first thought, with 35.1C registered at Floors Castle in Kelso.

Heatwaves have become more frequent, more intense, and last longer because of human-induced climate change, and that hot, dry weather is likely to fuel wildfires.

The world has already warmed by about 1.1C since the industrial era began and temperatures will keep rising unless governments around the world make steep cuts to emissions.

Met Office chief scientist Prof Stephen Belcher said Tuesday's temperatures were striking due to the large record-breaking margin and the extensive area of the UK experiencing the severe temperatures.

But "aggressive emissions cuts" could very sharply reduce the frequency of extreme temperatures, he told BBC News.