Image source, Reuters

And then there were four. Kenyans Wilson Kipsang, Dennis Kimetto, Eluid Kipchoge and Stanley Biwott are leading the way in the men's race. The pace has slowed a tad, the race turning into a chess match. It's more about tactics at this point, but who will make the crowning move?

Three of the six fastest marathon runners of all time are in the leading men's group. Eliud Kipchoge takes in some fluid before throwing his bottle onto the street. Hopefully he'll pick that up later.

Kipchoge looks over to his right, sees Dennis Kimetto by his side. Undeterred, he continues to up the tempo. They're working their way through London's streets like express trains.

The elite athletes look so comfortable on the TV - but the London Marathon is a speedy affair.....

Image source, Reuters

Nine kilometres away from the finish line are the men and they're still running at course record pace. Kenya's Eliud Kipchoge is leading the pack, recording 1:28.56 after 30k. Defending champion Wilson Kipsang and world record holder Dennis Kimetto are lurking behind him.

Image source, PA

Tigist Tufa runs down The Mall, looks behind her, notices no-one else is in sight and gives the crowd a wave. Many expected the Kenyans to dominate but it's Ethiopia's Tufa who wins the London Marathon in 2:23.21 (unconfirmed).

Image source, PA

With one mile remaining, Tigist Tufa is extending her lead in the women's elite race. The Ethiopian is comfortable enough to check her watch. She bursts down Embankment and it doesn't look like anyone can catch the 2014 Shanghai marathon winner.

Denise Lewis tries to ask Paula Radcliffe a few questions as the former winner crosses Tower Bridge, but no matter how hard she tries the former Olympian can't keep up with Radcliffe and we're left to assume the Achilles injury isn't giving Radcliffe too much grief.

Former Wales rugby union winger Shane Williams is running today and he's completed 10k in 50 minutes. He can't keep going at such a speed, surely?

The map which tracks Williams' run looks a bit confusing, but you can just about spot where he is.

Image source, London Marathon

We mentioned BBC Radio 2 presenter Chris Evans is among the runners and he has just been spotted. At the moment, he is on course for a time of four hours and 40 minutes which isn't too shabby.

The elite women are nearing the end of the road and it's too close to call. Meanwhile, the men's elite leading group now only consists of eight runners. They have 11 miles to go and you'd assume, considering the speed they're running at, more will drop off as they chalk off the miles.

Image source, Getty Images

After Joshua George's win in the men's T53/54 wheelchair race, the peerless Tatyana McFadden has made it an American double in the women's race.

McFadden has dominated women's wheelchair racing in the last two years, winning back-to-back marathons in Boston, London, Chicago and New York and this win was her third in a row in London after her Boston success last Monday.

Her winning time of one minute 41.13 seconds smashes her own course record of 1:45.12 - a superb effort from the woman whose nickname is 'The Beast' and she finished over two minutes ahead of Switzerland's Manuela Schaer.

Former Tour de France winner Chris Froome: , externalAt close to my height, Wilson Kipsang is 5 kgs below my ideal race weight!! maybe need to work a little harder

Steve Cram
BBC athletics commentator

Image source, AP

"Paula Radcliffe has to be one of the greatest sports people Britain has produced. Athletically, she doesn't have anyone to stand beside her in her event. She was a pioneer, and you don't often see that.

"Her marathon world record of two hours 15 minutes 25 seconds, achieved in London in 2003, took everyone's breath away. Sometimes an individual comes along and does something so out of this world that it reassesses everybody's thinking of what is possible.

"For women's marathon running, Paula is the leader. Three of the fastest times in marathon history all belong to her."

Talk on Twitter is that Paula Radcliffe's projected finishing time is two hours and 33 minutes, which is remarkable considering she only started training in Easter after six-weeks out with an Achilles problem.

The Guardian's Sean Ingle points out that the qualifying time for Rio 2016 is two hours and 42 minutes...

Brendan Foster
Olympic medallist and BBC athletics commentator

"The men are running faster than the course record at the moment. The sun is shining and it is drying out. There are 10 athletes in this leading group as they come up to the halfway point."

Image source, Reuters

The elite men trot over Tower Bridge with the crowd's cheers ringing in their ears. If they have time to look around them, they'll see the Shard to their left.

They're approaching the halfway mark and the best of the best are all in the leading pack of 10 runners and if they continue at this pace the course record will be broken.

We all watch the London Marathon and think "I'd love to do that". Ok, when I say all...

For most of us, thinking about it is is about as far as we get, but it doesn't have to be that way. There's a host of mass participation races out there, whether you fancy running one mile or slogging your way around 26.2.

BBC Get Inspired have put together a handy guide explaining everything you need to know. Next year it could be you.

Image source, BBC Sport

There is nothing worse than setting the alarm for a big day only for the cuckoo to refuse to come out of the clock, leaving you late and flustered and slow to the party.

Although, it could be an advantage if you want to soak up the cheers of the crowd. One runner got to have the start all to herself, 20 minutes after the actual race had started.

Steve Cram
BBC athletics commentator

Image source, Reuters

"The pacemakers have a tough job. The men have asked for a quick pace and it was a very fast opening 5km then it started to settle down. We have seen the pace-making go a little awry in recent years but hopefully not today."

Mike Costello
Athletics commentator on BBC Radio 5 live

"It is a fascinating head-to-head between the fastest man in history and the man he took the record from. But there are the top three of all time in the field and five of the fastest seven men in history - it's no wonder it's being called the greatest men's field in history.

"Dennis Kimetto is a remarkable story. He had his first international race as recently as 2011 at the age of 27. He's a raw talent who might be ready to go even quicker."