Back in school the teachers were in charge, and if you wanted to skip class legitimately, you needed a note from your parents.

In the same vein, Queen Elizabeth II will be asked to excuse 54 heads of government from attending all of the Diamond Jubilee celebrations that mark her 60 years on the throne next year.

The Jubilee clashes with Rio+20 — the UN Conference on Sustainable Development — at which world leaders are meant agree how to create a fair, green future for all.

And although UK Prime Minister David Cameron has pledged for his to be the “greenest government ever“, he plans to go to the Queen’s party instead.

Youth activists fear his colleagues from India, Canada, Australia and 50 other Commonwealth nations — home to 30% of the world’s people — will follow his example and endanger a successful outcome of the Rio conference.

They have created  a letter that citizens of Commonwealth countries can sign to ask the Queen to release their leaders to go instead to Brazil to “protect the planet for future generations” (press release here).

In the United States, the Natural Resources Defense Council has launched a similar campaign to get President Obama to attend the conference.

Can citizens force their leaders to change their travel plans and put the planet before protocol?

With just four days to go before the first Rio Earth Summit in 1992 US President George H.W. Bush said he would not attend. But public pressure helped to change his mind, and he went to Brazil and signed the UN Framework Convention on Climate Change.

But the biggest challenge will not be getting world leaders to attend the Rio+20 conference, but ensuring that they bring something to the table that they are willing to share.

[Update: On 4 November, Brazilian President Dilma Roussseff has announced that the Rio+20 conference will start on 20 June, instead of 4 June 2012, to avoid a clash with the Queen’s Silver Jubilee]