When the billionaire philanthropist Warren Buffett gave $37bn to the charitable foundation headed by his friend and bridge partner Bill Gates, below, in 2006, at once doubling its size and breaking the record for any donation in the United States, he said it was a moment that had "been coming for 50 years".

Such was the altruism behind this, the biggest transparently run charitable organisation in the world, set up by the Microsoft boss and his wife, Melinda, six years earlier, that Mr Buffett expressed real delight at transferring across 10 million shares from his conglomerate holding company, Berkshire Hathaway. "There's never really been any other plan in terms of where the money should go," he said. He now acts as one of the foundation's three trustees.

But from the moment Mr Gates set aside $126m for his new project in 2000, he was already focused on offering others opportunities: in the US, expanding IT and educational access; and abroad, alleviating extreme poverty and enhancing health care.

Its contributions to, and influence on, global health care is, at $800m (£400m) each year, comparable to that of the UN World Health Organisation and the US Agency for International Development.

Projects to which it has donated hundreds of millions of dollars include the Children's Vaccine Programme, HIV research, rice research, aid for earthquakes, and international water, sanitation and hygiene development. At home, the foundation works on the principle that "if you can get into a library, you can reach the internet", and focuses its grants on computer technology and libraries.