Turning round a story is one of the most difficult tasks in journalism – and rarely more so than in the case of Iran. Iran, the dark revolutionary Islamist menace. Shia Iran, protector and manipulator of World Terror, of Syria and Lebanon and Hamas and Hezbollah. Ahmadinejad, the Mad Caliph. And, of course, Nuclear Iran, preparing to destroy Israel in a mushroom cloud of anti-Semitic hatred, ready to close the Strait of Hormuz – the moment the West's (or Israel's) forces attack.

Given the nature of the theocratic regime, the repulsive suppression of its post-election opponents in 2009, not to mention its massive pools of oil, every attempt to inject common sense into the story also has to carry a medical health warning: no, of course Iran is not a nice place. But ...

Let's take the Israeli version which, despite constant proof that Israel's intelligence services are about as efficient as Syria's, goes on being trumpeted by its friends in the West, none more subservient than Western journalists. The Israeli President warns us now that Iran is on the cusp of producing a nuclear weapon. Heaven preserve us. Yet we reporters do not mention that Shimon Peres, as Israeli Prime Minister, said exactly the same thing in 1996. That was 16 years ago. And we do not recall that the current Israeli PM, Benjamin Netanyahu, said in 1992 that Iran would have a nuclear bomb by 1999. That would be 13 years ago. Same old story.

In fact, we don't know that Iran really is building a nuclear weapon. And after Iraq, it's amazing that the old weapons of mass destruction details are popping with the same frequency as all the poppycock about Saddam's titanic arsenal. Not to mention the date problem. When did all this start? The Shah. The old boy wanted nuclear power. He even said he wanted a bomb because "the US and the Soviet Union had nuclear bombs" and no one objected. Europeans rushed to supply the dictator's wish. Siemens – not Russia – built the Bushehr nuclear facility.

And when Ayatollah Khomeini, Scourge of the West, Apostle of Shia Revolution, etc, took over Iran in 1979, he ordered the entire nuclear project to be closed down because it was "the work of the Devil". Only when Saddam invaded Iran – with our Western encouragement – and started using poison gas against the Iranians (chemical components arriving from the West, of course) was Khomeini persuaded to reopen it.

All this has been deleted from the historical record; it was the black-turbaned mullahs who started the nuclear project, along with the crackpot Ahmadinejad. And Israel might have to destroy this terror-weapon to secure its own survival, to ensure the West's survival, for democracy, etc, etc.

For Palestinians in the West Bank, Israel is the brutal, colonising, occupying power. But the moment Iran is mentioned, this colonial power turns into a tiny, vulnerable, peaceful state under imminent threat of extinction. Ahmadinejad – here again, I quote Netanyahu – is more dangerous than Hitler. Israel's own nuclear warheads – all too real and now numbering almost 300 – disappear from the story. Iran's Revolutionary Guards are helping the Syrian regime destroy its opponents; they might like to – but there is no proof of this.

The trouble is that Iran has won almost all its recent wars without firing a shot. George W and Tony destroyed Iran's nemesis in Iraq. They killed thousands of the Sunni army whom Iran itself always referred to as "the black Taliban". And the Gulf Arabs, our "moderate" friends, shiver in their golden mosques as we in the West outline their fate in the event of an Iranian Shia revolution.

No wonder Cameron goes on selling weapons to these preposterous people whose armies, in many cases, could scarcely operate soup kitchens, let alone the billions of dollars of sophisticated kit we flog them under the fearful shadow of Tehran.