Unicef UK ambassador Ewan McGregor has warned "famine is looming" in South Sudan in the charity's latest appeal to help at-risk children.
A video featuring a host of film stars and musicians has been released to highlight the plight of children caught up in the Syria conflict.
The Olympic gold medallist Mo Farah and Scottish actor Ewan McGregor received honours at Buckingham Palace from Prince Charles.
Actor Ewan McGregor collected an OBE at Buckingham Palace today for services to drama and charity.
Wearing a kilt, the Scot said it had never been in doubt that he would come to the Palace in traditional garb.
He said: "I didn't have to think about it, that was always what I was going to wear. If you don't wear your kilt here, I don't know where you are going to wear it."
He also spoke about the possibility of returning to the role of Mark "Rent Boy" Renton, whom he played in director Danny Boyle's 1996 classic Trainspotting.
"I have not been approached officially, but I would be up for it and there has been talk about it happening in 2016, 20 years after we did Trainspotting.
"The sequel is called Porno, so I have to be careful about saying I am doing Porno in 2016."
But he ruled himself out of returning to the part of young Obi-Wan Kenobi in the new Star Wars sequel trilogy because the films he took part in were prequels.
In attendance with two of his four daughters and wife, McGregor also praised the volunteers at Unicef and Go Campaign, the children's charities he supports.
"The volunteers live and work in really difficult places - they are the people who should be awarded," he said.
Olympian Mo Farah has played down reports that he broke Wimbledon rules by filming play from the Royal Box and posting footage on social media.
Farah said after collecting his CBE, "I was filming but I took the film down from Twitter".
The double Olympic gold medallist also gave Andy Murray his backing to become the first British man to win the title at the All England Club for 77 years, saying, "I believe this year he can win it".
Ewan McGregor congratulated Mo Farah on "being an inspiration to so many people" before they posed for the cameras with their medals.
Olympian Mo Farah posed with a group of Beefeaters outside Buckingham Palace after receiving his CBE.
Actor Ewan McGregor and Olympic gold medallist Mo Farah have shown off their honours outside Buckingham Palace.
Actor Ewan McGregor has received his OBE from Prince Charles at Buckingham Palace.
Mo Farah said he is not tired of medals after Prince Charles joked the Olympian must be sick having so many of them as he collected his CBE.
The double gold medallist, who grew up in west London, triumphed in both the 5,000m and 10,000m at the London 2012 Games.
Speaking after receiving the award, Farah said: "I never in my life imagined coming to Buckingham Palace.
"I remember running past it in the mini-marathon as a kid when I was 13 and thinking it was so beautiful and taking pictures of the lion, so coming inside and receiving this award is great.
"Prince Charles said, 'You must be getting sick of so many medals' and to hear someone like the Prince of Wales knows who you are is just brilliant.
"I'm not tired of it at all, I just want to make my country proud and collect as many medals in my career as I can".