Billionaire philanthropists Bill and Melinda Gates have met with the Prime Minister at Downing Street as part of their latest campaign to boost help for developing nations.
The couple held private talks with David Cameron during a visit to London to launch the Living Proof campaign aimed at demonstrating the difference aid projects can make.
Mr Gates, the co-founder of software giant Microsoft, is devoting much of his vast fortune to tackling disease in the third world through the Bill and Melinda Gates Foundation.
Writing on his website about the visit to the UK, Mr Gates said he and his wife wanted to "thank the UK for its history of generosity and remarkable commitment to foreign aid".
"We are confident that spreading the word about what's working is one of the most important things we can do to motivate governments and others to invest in effective development aid," he added.
The coalition Government has ring-fenced international aid from public spending cuts as it aims to meet the United Nations' target of devoting 0.7 per cent of GDP to foreign aid by 2015.