THE woman’s voice on the phone was breathless and excited: "Can you be in London by 11am tomorrow? We desperately need you for a documentary."

I never wanted to be that guy who, upon retirement, says he never knew how he ever had time to work, but it is kinda true.

I checked my A4 diary and was surprised to find there were no fountain pen-inscribed entries for the rest of the week, so I zipped into Helensburgh for a haircut.

I was on the redeye to Heathrow in the morning and before I had had my third Americano of the day, I was through wardrobe, hair and make-up and sat ensconced under the lights and in front of the cameras at a studio in Soho.

The details of what Peter Tobin did during his reign of terror are well known. I say this guardedly, because there is a slim chance more horrors may yet emerge despite a lengthy cold case review by detectives the length of the country.

What the producers of this crime documentary needed from me was what journalists call colour, because I covered all the cases when I was a reporter. How did I feel? What did I do? What did I say?

As we approach the 20th anniversary of Scotland’s worst serial killer’s worst crimes, the whole episode is embedded in my memory.

I don’t sit and pore over them as a Bond villain might, but I have kept every notebook I used down my career because it was a legal necessity.

They are filed in a box in chronological order and before my departure I quickly removed the relevant ones, those filled with my scrawl from the disappearance and murder of Polish student Angelika Kluk and the discovery of her body in a Glasgow church in 2006, and Tobin’s trial a year hence.

I scanned them during the flight and taxi ride into London but in truth it was unnecessary. It is still all front and central.

Every morning during his trial in court three at the High Court in Edinburgh, Tobin would be brought in from the cells and eyeball me on the press bench behind the dock.

His black, evil eyes glared at me from beneath hooded lids.

The first morning this happened, he spooked me and I looked away. Thereafter, every day of the six weeks of the trial, I held his eye.

As I poured out the very material the documentary producers wanted, and much, much more, I realised the profound effect the whole episode had on me despite the passage of time.

And as I headed for my hotel that night, understanding the enduring impact 20 years on, I could only imagine how his victims’ families must feel today.