The phone beside my bed jolted me awake at 1.30am on Sunday, December 14, 2003. I had barely got to sleep after another 18-hour day.

“Sorry to wake you, sir.” It was my assistant military aide, Major Pat Carroll. He said that General John Abizaid, head of US central command, needed to talk to me right away on a secure line.

The clunky red STU-III scrambler phone in my house didn’t work so I started throwing on my clothes to go to my office in Saddam Hussein’s old palace. Abizaid and I spoke almost daily but it was very unusual for him to call in the middle of the night. And on a secure line. This must be either very good or very bad news, I thought.

Fifteen minutes later I arrived in my dimly lit office. My new deputy, Dick Jones, was there with a man from the CIA station. I asked Dick what was up. Turning to the intel officer, Dick said: “I don’t want to steal your thunder.”

The agency man said: “We think we’ve caught Saddam.” I picked up the red phone and was put through to Abizaid at his headquarters in Qatar. “John, what’s this about Saddam?” “We think we’ve got him,” he replied. “Special ops guys found a dirty, bearded man at the bottom of an unguarded spider hole just outside Tikrit.”

“How do you know it’s Saddam?” I asked.

“When our guys pulled him out of the hole, he said, ‘I am Saddam Hussein, president of Iraq’,” John said. “They looked him over and he has the scars and a tattoo we know Saddam has.”

Abizaid and I also knew that for years Saddam had used doubles to confound his enemies. So I asked what more we could do to confirm that we had really captured Saddam.

“We’ve brought him down to Baghdad,” John said. “We’ll clean him up and show him to some of the other top regime leaders we’ve detained. We’re also going to rush a DNA sample to Germany for verification. We’ve got a C-17 standing by.”

“John, we’ve got to be 100% positive,” I emphasised. “We’ll be the laughing stock of the world if the news gets out and it’s one of his damn doubles. How long will the DNA check take?” “My guys tell me it’ll be 24 to 36 hours.”

I went back to bed but I couldn’t sleep. For many months after liberation we had been chasing every stray rumour or fragmentary report about Saddam’s whereabouts. At one point we had a report from a “usually reliable source” that he was riding around Baghdad in the back seat of a taxi, wearing a long white beard and a red hat. “Sort of like Santa Claus,” as one sceptical analyst put it.

We had switched strategies after concluding that Saddam had separated from the high-level people soon after liberation, knowing we’d be looking for them. Instead we started going after low-level “facilitators”. Servants, gardeners and chauffeurs who had worked for Saddam might provide a better path to the fugitive dictator. So military intelligence and the CIA had built a database of gofers and their contacts. Had we now finally caught that son of a bitch?

After about two hours of fitful sleep, I rose for a hectic day. Brigadier General Barbara Fast, the coalition J-2 (senior intelligence officer), arrived with Lieutenant General Ricardo Sanchez, the commander of all coalition forces in Iraq. Rick looked even more sleep-deprived than I did.