He’s worried the Daily Mail will have got there first. Colin is counting on us to sign her up and get her under contract. He’s so determined to splash on the reunion between the Angel of Death and her sister that he tried to send an agency reporter ahead of us, but Lawrie was adamant: his contact, his story. He refused to give away the prize of this address, especially to an agency, who might sell it on to a rival news organization at an inflated price.

4 Hawberry Lane, Coggsbridge, Essex.

Her name is Catherine Allen now. Married to Edward Martin Allen, who was born on 15 April 1979.

During the long and treacherous drive from Kent to Essex, Lawrie also pulled the birth and marriage certificates of their extended families, and scoured the electoral roll. We now know that Mr Allen’s parents – Carol and Stephen – are still alive and based in Brighton. He has a sister called Hannah in Bassenthwaite, Cumbria, living with a man named Mark Ashton. Lawrie used the details in today’s Sun story to trace Pamela Carter’s mother in Yardley, Birmingham, and with that information, an aunt in Nottingham and a cousin in Tring.

We know that Catherine Allen has a daughter, Honor, who is twelve years old.

We know that the youngest Carter sister has no social media accounts, no employment history and has been living under the radar for thirteen years.

We know everything now.

The house is not a house at all, but a cottage. There’s a light in the window and a holly bush on the front lawn covered in red berries. It looks homely and wonderful.

A car is parked at the end of the lane. Ordinarily, I wouldn’t give it a second glance, but its windows have steamed up which means someone’s inside. My antennae twitch. Another journalist.

Lawrie has wound down the car window and is looking up and down the street, sizing up the competition. This is the part of the job I dislike the most. Knocking on doors, intruding into private lives. But it’s a necessity today, a justifiable public interest in this story that’s lacking in celebrity bikini shots and bankruptcies.

As we’re contemplating our next move, a woman with a dark fringe, wearing flowery wellington boots, hurries into number four.

She’s halfway up the garden path before we react, and then Lawrie is out of the car and running after her, calling out her name.

She spins around, her mouth forming a circle of surprise, and I can’t help thinking how vulnerable she looks. Her hair is a different colour, but I can see in her face the child she was. She doesn’t see me, but I’m not sure she would recognize me these days. She hesitates for a few seconds, and then lowers her head and disappears into the house.