"There's been an existential question mark over the Commonwealth for some time," says a seasoned diplomat in its secretariat in London.

"The Commonwealth has been dead, absolutely dead, for the past eight years," laments Richard Dowden, director of the Royal Africa Society, taking a swipe at the outgoing secretary-general, Kamalesh Sharma, an urbane Indian diplomat who has run the show since 2008.

As Queen Elizabeth nears 90 after 64 years as its titular head, some wonder if the club will survive when she goes.

Ask citizens of the 53 countries that make up the Commonwealth what it is for, and most will shrug. A few years ago the Royal Commonwealth Society conducted a poll asking if respondents would be "sorry or appalled if your country left the Commonwealth." People in its poorer members were likeliest to answer "yes"; those in Britain, Australia and Canada tended to indifference. Few knew much about it; a quarter of Jamaicans thought its head was Barack Obama.

The modern Commonwealth was born in 1949, partly thanks to Jawaharlal Nehru, independent India's first prime minister, who had declared his nation a republic but wanted to stay friends with the former imperial power and other former British dominions.

As other ex-colonies joined, "Commonwealth values" (never precisely defined) were promoted. Under a dynamic leader from Guyana, Sir Shridath Ramphal, from 1975-90, the grouping gained clout in world councils.

The Commonwealth's purpose is twofold: to advance democracy and human rights; and to aid economic development. But on the first score it lacks a proper mechanism for enforcement. And on the second, it is not a big provider of cash.

It was in 1991 that heads of government declared that the Commonwealth should bolster human rights and democracy. The organization gained respect for the teams it sent to observe elections. In 1995 an action group was set up to deal with "persistent and serious violators" of those principles. Since then several offenders, including Nigeria, Pakistan, Fiji, Gambia and Zimbabwe, have been ejected or shamed into leaving, usually temporarily.

But under Sharma, the organization is generally thought to have atrophied, especially as a vehicle for upholding democracy and human rights.

He says that quiet persuasion has done more to advance democracy than public denunciation would have, for example when Guyana's government stepped down a year ago after narrowly losing an election.

To give him his due, the Commonwealth acts by consensus. Countries are meant to carry equal weight in discussions and there are few sanctions short of expulsion.

And despite its weaknesses, the Commonwealth is a club that countries want to join. Though war-ravaged South Sudan is the only one formally on the waiting list, a string of others have been dandled as "possibles": Algeria, Burma, Burundi, Ireland, Kuwait, Nepal, Palestine and Yemen.

The organization's real force is as a unique all-purpose network, whose embrace includes trade, education and an array of 180-odd professional bodies, from law to dentistry.

British Prime Minister David Cameron praises the club's ability to "bring Pakistan and India together in a useful format"; its support for his campaign against global corruption; its climate-change advocacy ahead of the global conference in Paris; and its "forum for discussions in Africa and in the Caribbean, which can feel ignored and unloved."

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