It was 1983 and I was doing a short stint at Number 10. Israel and Lebanon were at war. Thousands were trapped in Beirut, including many Britons.
Other countries were getting their people out. But Margaret Thatcher's press secretary Bernard Ingham told the morning lobby that while the government was being watchful, no British evacuation was under way.
It was a deliberate lie. A lightly protected convoy had been assembled in secret. Even as Ingham denied the fact, it was speeding to a coastal rendezvous with the Royal Navy.
Terrified that it was an obvious target for hostage taking or worse, the government had decided to put potential attackers off the scent. A news blackout was not enough. It needed a smokescreen of credible media stories about the laggard Brits leaving their nationals to languish.
The lobby duly did its stuff. Within an hour, news bulletins were full of the British government's failure to look after its citizens properly.
Next day, all was revealed. By then, the convoy had reached a beachhead protected by Royal Marines, and all were rescued safely.
In true style, Ingham made no apologies for lying to safeguard lives, but he did offer the lobby his resignation, saying he would understand if they felt they could no longer trust him.
They turned him down flat. Her Majesty's Navy had saved our fellow countrymen, and so Her Majesty's fourth estate duly saved Ingham.
In the heady atmosphere of relief, someone joked that at least the evacuees would get a free ride home. But Number 10's FCO press officer was a former consul, experienced in such matters. Ignoring desperate semaphore signals from Ingham's famous eyebrows, he caught the mood of openness and put us all right.
To the lobby's ecstatic outrage, he declared that nothing in life was free, including being ferried by frigate to Cyprus. What is more, our plucky evacuees would have to sign a promise to pay up before boarding.
Thus was a PR disaster snatched from the jaws of intrepid rescue.
Be warned: the truth always gets you in the end.
Mike Granatt is a partner at Luther Pendragon and former media adviser at the House of Commons.