Thousands of running enthusiasts joined celebrities and sports personalities today for the Sport Relief London Mile.
Conservative MP and former Strictly Come Dancing star Ann Widdecombe started the first wave of the charity run, which included Spice Girl Melanie Chisholm, model Nell McAndrew, EastEnders actors Matt Lapinskas and Tony Discipline and Olympic and Paralympic medallists Allyson Felix and Chris Holmes.
As she kicked off the event, which included runners dressed as elephants, tigers, polar bears and robots, Widdecombe said: "I would like to say good luck to all of you, especially those dressed as animals.
"It's a good thing I'm not down there or I would be coming in at about 3pm this afternoon."
Elsewhere in the UK, David Cameron was among those who ran, along with his wife Samantha and their two eldest children, Nancy and Arthur.
Under blue skies and bright sunshine the family took part in an event alongside around 200 others at a sports field outside Great Missenden in Buckinghamshire, just a few miles from his country residence Chequers.
Dressed in a white Sport Relief T-shirt and knee-length black shorts, Cameron was one of the first to cross the finish line.
He had sprinted ahead of his wife, who ran the route more slowly with the children.
The Prime Minister congratulated other young competitors after he finished and waited for the rest of his family before they departed in a Range Rover.
It was the second time that Cameron had taken part in the Sport Relief Mile.
Back in 2010, before he became Prime Minister, he was the first across the finish line on London's South Bank.
McAndrew was the first to cross the finish line on the Mall in central London, saying it was her "competitive streak" that spurred her on.
She said: "As I'm training for the marathon at the moment I was wishing this was the last mile of the marathon and I felt this good.
"It's fantastic everyone is in fancy dress, it's such a lovely atmosphere and I think anything that gets so many people across the UK active is such a fantastic thing. They are helping to raise money at the same time, too.
Swimmer Holmes, who has won nine Paralympic gold medals, ran with 200m Olympic silver medallist Felix.
Holmes joked: "I was trying to make her go faster but she wouldn't."
He added: "It's great to stand on the gold medal rostrum but what's even more important than that is giving people the chance to realise what they can achieve in sport.
"Bringing the Olympics home to London means people being inspired by world class performances in a world class city. If everybody looks at Olympic and Paralympic values and thinks what can I do different in my life that will be an amazing thing."
Spice Girl Chisholm, who ran three miles during the event and finished looking happy but out of breath, said: "The Spice Girls had a long history with Comic Relief and now we have Sport Relief and they do such amazing work.
"To make raising money for something so awful so much fun is great.
"I will be feeling good when I get my breath back!"
Little Britain star David Walliams, who famously swam 140 miles along the length of the River Thames for Sport Relief, was spotted at the event, but it is not yet known if he will be donning his trainers for the run.
Pop stars JLS, actress Miranda Hart and Olympic medallist Dame Kelly Holmes are all due to take part in the run later today.