Small coincidences have big consequences. It's a truism, but in writing my book Philomena – now made into a startlingly moving film by Stephen Frears, Steve Coogan and Judi Dench – two events showed how true a truism can be.
The first concerned myself and an unexpected meeting at a party in 2004. I'd recently lost my job as a UK government communications director after a row with Alastair Campbell and Stephen Byers and I was at a loose end.
A woman I didn't know said she had a message for me from a friend. She knew I'd worked for many years as a BBC foreign correspondent and she asked if I'd help her solve a family mystery. It set me on a five-year search for a man I'd never met.
I met the friend, Jane, for a coffee at the British Library.
She said her mother, Philomena, had revealed a secret she had kept for 50 years – she had a son she had never spoken about to anyone. Philomena had been a teenage single mother in Ireland at a time when sex outside marriage was considered a sin. Jane said her lost brother would now be in his early fifties and they were both desperate to find him.
I was intrigued, but my journalism had been about wars, international crises and superpower summits. I wasn't sure about writing a human-interest story. What convinced me to do so was meeting Philomena herself. She was friendly, bright and likeable – qualities in short supply in Westminster and Whitehall. We hit it off straight away.
Philomena told me she had given birth in a country convent at Roscrea in County Tipperary on July 5, 1952. She was just 18 when she'd met a young man who bought her a toffee apple on a warm autumn evening at the county fair.
"I had just left convent school," she remembered. "I went in there when my mother died, when I was six and a half, and I left at 18 not knowing a thing about the facts of life. I didn't know where babies came from."
Philomena's family had "put her away" with the nuns. And after her baby, Anthony, was born, the Mother Superior warned she would face damnation if ever she revealed her guilty secret.
"All my life I couldn't tell anyone," Philomena told me. "We were so browbeaten, it was such a sin. It was an awful thing to have a baby out of wedlock."
Philomena was one of thousands of Irish women sent to convents in the '50s and '60s, labelled moral degenerates by a Church hierarchy who ruled that they must not be allowed to keep their children. For the Church, it was a lucrative deal. The Government paid a pound a week for every woman in the Church's care, and two shillings and sixpence for every baby.
After giving birth, the girls were allowed to leave only if their family could pay £100. Those who couldn't afford it – the majority – were kept in the convent for three years, working in kitchens and laundries, or making rosary beads, while the Church kept the profits from their labour.
Philomena served her three-year sentence in the laundry at Roscrea and caring for her son.
But at Christmas 1955, she was told Anthony would be given up for adoption. "Oh, Anthony was gorgeous," Philomena told me. "He was a lovely, gentle, quiet lad. All my life I never forgot him. I prayed for him every day. I just want so badly to know what happened to him."
But by piecing together passport records, archived documents and fleeting references in old newspapers, we found that Anthony Lee had been offered to an American Catholic couple, Marge and Doc Hess, from St Louis, Missouri. In my research, I came into possession of Marge's diary from 1955, which revealed that the Hesses had three sons and wanted to adopt a daughter.
Marge Hess had flown to Ireland looking for a little girl. Her diary tells how she found three-year-old Mary McDonald in the convent at Roscrea; and it recounts the coincidence that led her to adopt Anthony Lee.
When Marge leant down to pick up her new daughter in the nursery, a little boy came running to give her a kiss. He was Mary's best friend, and Marge fell for him at once.