At its simplest, journalism is about telling people things they don't know. So when the Ministry of Defence approached the BBC - along with other parts of the UK media - to ask us not to tell our audiences about a possible deployment of Prince Harry to Afghanistan, it was something we thought long and hard about.
A news black-out is unusual, but not unique. An agreement exists between the police and the media over the reporting of kidnaps - the police have the right to request that media organisations don't report an abduction while negotiations are under way, in case it makes the release of the hostage more difficult; in return, they accept the responsibility to update the media regularly and reveal the full story, on camera, once the situation has been resolved. When lives are at risk, it's not always helpful to have things played out in the glare of publicity.
Last summer - on the day my colleague Alan Johnston was released in Gaza - the Chief of the General Staff, Sir Richard Dannatt, met editors to make the case for a voluntary agreement. He was very candid; Harry wanted a career in the Army and he needed to be able to be deployed to do what he'd been trained to do, even if it was just for a day.
After five months of discussions, using the kidnap agreement as our model, the MoD and the UK media reached an understanding; we wouldn't speculate or report on the prince's deployments to minimise the danger to him and to others. In return, we'd get access to him before, during and after his time in Afghanistan. It was a voluntary agreement - any of the organisations could have decided to leave at any time. We - and the other UK broadcasters and newspapers - were clear that we would not report his deployment.
So, for the past ten weeks, the BBC, ITV and Sky News have been filming with Prince Harry - the first time we've been up close and personal with him. We interviewed him at Clarence House in mid-December, just before he was sent to Afghanistan, we spent some time with him at the start of January when he was settling in at a remote base in Southern Helmand Province, and most recently, we filmed with him last week at a new location in Helmand Province.
In truth, the surprise is that the agreement lasted so long. We - and the other UK broadcasters - were clear that we would not report his deployment. But nor would we deceive our audiences.
On Christmas Day, when neither Prince William nor Prince Harry attended the regular service with other members of the Royal Family at Sandringham, we agreed with the Ministry of Defence that they would say that both princes were spending Christmas with their regiments - William volunteered for Christmas duty to help out his brother! It prompted some inquiries from one US TV network who had to be briefed on the story.
More recently, on Tuesday, the German newspaper Bild ran a diary story asking "where's Prince Harry?" and speculating that the gossip was that "he'd gone to war". We agreed that while the story was speculative and confined to diary pages, that we would not break the agreement we'd reached with the MoD.
Then yesterday, the Drudge Report - the online US website famous for breaking the story of Bill Clinton's relationship with Monica Lewinsky - put the story on its front page. The game was up. We, and the other broadcasters, agreed with the Ministry of Defence that the story was out and it would be wrong not to tell our audiences what had been going on.
We don't do this stuff lightly - there are no other "voluntary agreements" in place at the moment, there's nothing else we're not telling you. Until yesterday, only a handful of people in the BBC knew about the story - trust me, keeping secrets from other journalists is hard work! Our job normally is to make these things public, not keep them from you. But this was never just about Prince Harry's safety, it was also about the security of the soldiers serving with him. No editor wants to be responsible for increasing the risk they already face from the Taleban. Nor do I think our audiences would have thanked us for doing so.