Baroness Tanni Grey-Thompson
11-time Paralympic champion

Most of this field have done the Tokyo and Boston Marathons over the last few weeks and will be going on to doing Seoul next week so they are all able to do back to back marathons - the recovery is much much quicker than the able bodied runners. 

This is where it starts to get interesting when they come down these hills - they will be going about 30 miles per hour. 

At this speed, even hitting a stone on the road will knock you out of your chair. 

Good to see plenty of people lining the early stages of the route as the first group of wheelchair racers come by.

Japan's Hiroyuki Yamamoto is leading the pack at the moment as the racers get their first brief respite with a downhill stretch. David Weir is in third, head tucked in tight. And the sun has made an appearance too!

Image source, BBC Sport

Get married in the morning, then run a marathon in the afternoon? Easy.

A massive congratulations to Duncan and Jackie, who tied the knot on the Cutty Sark this morning before running today's marathon - and their wedding gear will now become their running gear.

Jackie credits running with keeping herself positive and fit while she underwent chemotherapy for breast cancer.

The couple, who are racing for the Willow Foundation and Breast Cancer Care, are also taking part in a fundraising trek along the Great Wall of China for their honeymoon.

Marcel Hug is leading the men as we reach the first mile mark, with David Weir in third.

Back on the start line, the World Para Athletics Marathon World Cup Race for ambulant athletes has got underway. 

Manuela Schar lost out on the London title in 2016 by an agonising one second - and she's finished behind McFadden in three other marathons in the last 12 months.

The Swiss has finished second to McFadden for the last three years at the London and New York marathons.

She won the Berlin Marathon in September but was forced to settle for second place in Tokyo this year, behind American Amanda McGrory.

Image source, Getty Images

Baroness Tanni Grey-Thompson
11-time Paralympic champion on BBC Two

David Weir has said he won't compete again for GB on the track. I dont think he's done yet.

 He needs to wait. I dont want him making a decision on the back of today.

I love him as athlete. He's still got so much potential left as a wheelchair racer. He hasn't hit his prime yet.

Helen Glover and Heather Stanning, big grins on their faces, press the buzzer - and they're off!

The wheelchair racers are on the start line, ready to get the day under way.

There's a massive cheer from the stands for David Weir.

The oldest London Marathon runner today is Ken Jones. He is 83 years old and he wanted to pass on his best advice having completed every London Marathon - it's his 37th today. 

"When it gets difficult at about 21 miles, you have to dig into your reserves but that's when the crowds help."  

As a veteran of the London Marathon herself, BBC weather forecaster Elizabeth Rizzini knows exactly the best type of weather for running. 

Here's her forecast for Sunday.

On that note - what sort of weather will be greeting our runners today?

Cool and cloudy - looks about right for running a marathon.

Image source, Shooting Star Chase

Switzerland's Marcel Hug claimed the title back in 2016, in a year that saw him win ever World Marathon Majors race and marathon gold at the Rio Paralympics.

Born with spina bifida, the Silver Bullet - a nickname given to him because of his racing helmet - won his first London title in 2014.

He also has a ton of world and European titles to his name after 21 years of competing.

"Anything can happen in wheelchair racing and the field is stronger than ever," he said. 

Image source, Getty Images

Ellie Thomason
BBC Sport at London Marathon

Image source, BBC Sport

Just under two hours until the mass start, but most nearby stations are packed to the rafters as runners and spectators arrive nice and early.

"This is the race I love; it’s been in my blood since I was eight years old."

David Weir retired from track racing in September last year and he's could retire from all racing at the end of today's marathon.

This is his 18th consecutive appearance in London - he won his first London title back in 2002 and he's won five more since then, along with 10 Olympic medals.

He's in good form, too, having won the Paris Marathon at the start of the month in one hour 29 minutes 21 seconds.

Image source, Getty Images

About 40,000 runners will be taking to the streets of London today, with the Elite Wheelchair Races getting us underway.

For the elite runners today there's the extra impetus of qualifying for World Championships selection for the British team when the event takes place in August.

Image source, Getty Images

• Are you running in today's marathon and want to thank someone for inspiring you to run?
• Would you like a shout out for a pal to wish them good luck on the start line? 
• Are you actually at the start line and want your start-line-selfie published for all to see?

Then get in touch using #GetInspired or if you need a few more characters then you can text us on 81111. 

BBC Two

We're currently live from the start line on BBC Two with Gaby Roslin and the team. There's also commentary on BBC Radio 5 live sports extra and BBC Radio London, which you can listen to at the top of the page from 09:00 GMT.

There's extra coverage of the elite races and the finish line on Red Button, online, Connected TVs and the app.

Right, here's how things are lining up today:

08:55 - World Para Athletics Marathon World Cup Wheelchair Races

09:00 - World Para Athletics Marathon World Cup Races

09:15·- Elite Women

10:00 - Elite Men and Mass Start

26.2 miles. 750,000 bottles of water. 35km of banners. 40,000 finishers medals.

It's time for the 2017 London Marathon!

To everybody running today, we wish you the very best of luck. We'll be here to guide you through the elite events and share the best stories from this year's marathon.

Image source, Getty Images