An estimated 500 people ran in honour of missing loved ones this morning, during the annual Miles for Missing People 10k in Clapham Common.
Participants wore posters of people registered missing, as both an appeal and a tribute to those who have disappeared.
More than £20,000 has been raised from the event so far, organised by charity Missing People.
Among the runners were Kate and Gerry McCann, whose daughter Madeleine disappeared during a family holiday in Portugal in 2007.
A runner carrying an appeal for missing Anthony Stammers, 27
Peter Lawrence, whose 35-year-old daughter Claudia vanished while walking to her home in North Shields in 2009, gave a speech before the runners set off.
Also watching the race was Rachel Elias, Missing People spokeswoman and brother of former Manic Street Preachers guitarist Richie Edwards, who has been missing since 1995.
Claudia Lawrence's father Peter delivers a speech
Missing People communications manager Spencer Gasson said: "It was a brilliant day, with fantastic weather. There was a really good vibe about it this year.
"We also had a number of performances from the Rock Choir in London who sang a few songs.
"But the main thing is people running had missing people posters on their backs.
"Some were running for missing family members like Gerry and Kate, others just took posters and ran for people they didn't know.
"The nice thing is, that way, the missing person is still remembered."
Madeleine McCann's parents Gerry (above) and Kate taking part in the Miles for Missing People 10k, with Gerry carrying a picture of his missing daughter on his back (below)
The Miles For Missing People 10k is part of Forget-Me-Not month, which in itself is a build up to National Missing Children's Day on Sunday, May 25.
That day will see the launch of the enhanced Child Rescue Alert system, a partnership between Missing People, the National Crime Agency and communications firm Groupcall.
It will see messages sent out via social media, text and email, alerting the public to a child who is known to have been abducted or is at risk.
About 500 people took part in today's run, which has so far raised more than £20,000 for Missing People
Missing People will also be tweeting appeals for missing children every half hour for 24 hours on May 25, and is asking followers to retweet the messages to as wide a audience as possible.
For more information about Missing People and its work, visit the website.