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Eliud Kipchoge, who became the first athlete to run a marathon in under two hours in 2019 and is widely regarded as the greatest distance runner in history, is back at the London Marathon for the first time since 2020 this year.

The Kenyan dropped-out at his final Olympic Games in Paris part way through but still believes he can compete for a fifth victory in London.

The 40-year-old is joined in the elite men's race by defending champion Alexander Mutiso Munyao and Ethiopia's Olympic champion Tamirat Tola.

Despite their presence, many eyes are on half marathon world record holder Jacob Kiplimo, who makes his debut after becoming the first person to run a half marathon in under 57 minutes in February.

He may well be the man to beat today.

In terms of British interest, Olympic and world triathlon champion Alex Yee makes his highly-anticipated marathon debut.

Mahamed Mahamed and Philip Sesemann are among the British men aiming to push towards the front, with Emile Cairess having withdrawn.

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Swiss great Marcel Hug bids for a seventh - and fifth consecutive - London Marathon victory in the men's wheelchair race.

He has been utterly dominant in recent years and also won a third Paralympic title in a row in Paris last summer.

The women's Paralympic champion and Hug's compatriot Catherine Debrunner also goes for a third London victory following five golds at Paris 2024.

David Weir is back again for a 26th consecutive appearance in London.

In the women's event, last year's Boston Marathon champion Eden Rainbow-Cooper will aim to improve on her best London finish of third in 2022.

David Stancombe and Sergio Aguiar are two of those taking part today.

Their daughters Elsie and Alice were two of the three girls killed at a dance class in Southport last year.

David and Sergio are running to raise money for charities in their daughters' names.

Sergio told BBC Breakfast he talks to Alice when he's running alone.

"I tell her to keep going with me, that we're going to do this together, you're going to be with me - always."

David says his daughter would be very proud of his efforts.

The pair watched coverage of the marathon on TV last year and she told him he should run the race in honour of her grandmother.

"A little bit of me was like, 'oh yeah, alright Els,'" David said. "I just never thought I would be running it for these reasons."

Read more on their story and watch the BBC Breakfast video above

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Tens of thousands will be taking part today, each for their one special reason. We'll bring you as many of those as we can throughout the day but the initial focus will be on the elite races.

Here are the key timings:

• 08:50 - elite wheelchairs
• 09:05 - elite women
• 09:35 - elite men
• 09:35-11:30 - mass event

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As Matt says below, it's going to be a hot one today with temperatures set to get up above 20 degrees.

If you're reading this from behind the start line, take note.

Be careful. Pace yourself.

There will be 18 showers on route to help cool participants down, ice available and extra water at the designated stations.

Race director Hugh Brasher has also advised runners to wear lightweight clothing and to be caution with their speed in the heat.

"That's the number one piece of advice," he told the BBC.

"It's not the day to try and run your fastest marathon. Slow down, smile, enjoy it.

"We have absolutely got the provisions ready and waiting."

Matt Taylor
BBC Weather

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Afternoon warmth will be the main weather talking point of this year's marathons in London and Manchester.

Despite a slightly fresh morning, with temperatures on the starting line around 9C first thing, by the afternoon temperatures are likely to peak at 18/19C (64/66F) in Manchester and around 21/22C (70/72F) in London. This will likely make it London’s fourth warmest marathon in its history, the warmest being in 2018 when the mercury hit 24.2C (76F).

So be prepared to stay well hydrated, and don’t forget some suncream too – it’ll be a dry and largely sunny day, although it may cloud over later in Manchester. Oh, and if you are struggling with hayfever right now anti-histamines might be a good idea too as tree pollen levels become high or very high.

Much of the talk in the build-up today has been about the weather. Here's the all-important forecast...

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The 45th London Marathon is aiming to break a record and become the marathon race with the most competitors.

There are expected to be more than 56,000 people taking part this year, from the elite field through to those dressed as dinosaurs or carrying pigeons.

The record number of finishers is 55,646 finishers at last year's New York Marathon. This month's Paris Marathon also had 56,950 starters but fewer finishers.

London is hoping to beat both numbers.

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Hello, hello.

It's that time of year again.

Once a year, on a Sunday in April, London comes together to celebrate one of the great sporting occasions.

First the elite racers will set off - and the fields are stacked with Olympic and Paralympic champions - then thousands will take the streets each of their own special reasons to run 26.2 miles.

It'll be emotional...

It's a day in the British sporting calendar like no other...