Sherpas help leaders prepare for political summits
Sherpas are the tough and resilient Nepalese guides who help mountaineers scale Himalayan peaks.
But the word also refers to the faceless diplomats who lay the groundwork for high-profile international meetings such as the G8 and the G20.
The summits they prepare for are no less arduous. Like the real sherpas, they must have stamina and skill.
Their work - numerous face-to-face meetings, conference calls and e-mail exchanges - determines whether a summit will be a success.
In many cases, they will have drafted the communique far in advance of the leaders' actual meeting.
"There are many late nights and early mornings," says Dan Price, a former US sherpa for President George W Bush.
"You tend to form close bonds with your colleagues, because you are working usually under great time pressure."
Mr Price doesn't know where the term originated but says it has been around a long time.
The analogy extends to the sherpa's aides, who are sometimes called yaks.
Mr Price was a relatively fresh face in diplomatic circles when he took on the role. Before joining the Bush administration he was a trade lawyer in Washington.
G20 LONDON SUMMIT
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The G20 countries are Argentina, Australia, Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, Saudi Arabia, South Africa, South Korea, Turkey, the United Kingdom, the US and the EU.
He is now the senior partner for global issues at international law firm Sidley Austin.
Mr Price won't be drawn on whether he misses the job.
Sherpas rarely talk publicly about their role.
"It was a great deal of fun," he says diplomatically.
"But you feel very keenly the responsibility to try and come up with common positions and strong substantive outcomes."
"You are also managing political expectations. Not only the individual members of the summit but the public at large."
The current British sherpa is Jon Cunliffe.
A former second permanent secretary at the Treasury, he is now the prime minister's advisor on international economic affairs and Europe.
Mr Price says Mr Cunliffe is likely to have his work cut out at the G20.
Sherpas are usually associated with the more exclusive G8 meetings but now the G20, which includes emerging economic powers like China, is fast becoming the more important forum.
This means many more meetings, conference calls and e-mail exchanges and a greater array of political masters to please.
"Their agenda will necessarily somewhat broader," says Mr Price.
"But the summit rests safe in his hands," he adds.