British journalist Martin Sixsmith has uncovered a nightmare story about what happened to a 3-year-old Irish boy who was taken from his mother in 1955 and sold for adoption by Irish nuns to a family in the U.S.

In 1952, an 18-year-old woman called Philomena gave birth to her first child in a convent in Roscrea in County Tipperary.

Philomena had just left convent school and was as innocent in the facts of life as many of her generation.

She had been sent to the school when she was just six, shortly after her mother died, and her horrified family sent her back to the convent when they discovered she was pregnant.

Philomena was one of thousands of Irish women who were ripped from their own families and then treated brutally by the nuns.

Sixsmith discovered that the Irish state paid the nuns a significant amount for the "care" of the mothers and babies (£1 a week for a mother and 2s 6d for each baby). The women were free to leave at any time within the three years - once they could pay a £100 fee - a king's ransom.

The mothers would then take care of their children (while earning the convent a significant income) until the children were three years old when the nuns would then sell the children for adoption.

The mothers were made sign a legal undertaking to never search for their lost children.

In 1955, Philomena Lee signed a paper that said.

"I do hereby relinquish full claim forever to my said child Anthony Lee and surrender him to Sister Barbara, Superioress of Sean Ross Abbey . . . to make my child available for adoption to any person she considers fit and proper, inside or outside the state.

"I further undertake never to attempt to see, interfere with or make any claim to the said child at any future time."

Anthony was taken away from Philomena at Christmas 1955. And, even though she was then allowed to leave the convent, her father refused to take her.

He told everyone she had "gone away." Not even her sisters knew what happened to her.

Philomena was sent to an industrial school in Liverpool to work for the nuns. Her life improved in Liverpool. She became a nurse and then got married in 1959 and had two more children.

She went back to Roscrea several times to see what had happened to her son. But the nuns refused to help. They presented her letter signed back in 1955 as grounds for refusing to tell her.

But while Philomena was searching for Anthony, Anthony was searching for Philomena. He traveled from the U.S. to Ireland twice, in 1977 and 1993, to try and find his mother. The nuns too turned him away.

Anthony - who had been sold to a middle class couple from Missouri for about $2,500 - was now named Michael Hess.

A gay attorney, he worked for the Republican National Committee and kept his sexuality a close secret.

However, by 1993 he had contracted AIDS and wanted to see his birth mother before he died.

He arrived in Roscrea in 1993 to make an emotional appeal to the nuns for the information that would help him find Philomena.

The nuns didn't care.

They were unmoved by his pleas for help.

But they did offer him a paid gravestone at the convent.

Michael had appealed to the Mother Superior to let him be buried in the convent. He wanted to use the gravestone as a way of letting his mother know where heas.

The nuns allowed him to do that - in return for a hefty donation to the Church.

And so, when he died in 1995, his remains were brought to Roscrea for burial at the very convent where he had been so cruelly stolen from his mother in 1955.

His gravestone reads: "Michael Hess, a man of two nations and many talents,' the inscription reads. 'Born July 5, 1952, Sean Ross Abbey, Roscrea. Died August 15, 1995, Washington DC."

Nine years later, in 2004, Sixsmith would begin researching the vanishing paper trail at the convent and eventually traced Anthony's path from Roscrea to Missouri to Washington D.C. and back to Roscrea.

Tragically, Philomena's lasting memory of her son is a three-year-old boy peering out the back of a car as he was taken away from Roscrea at Christmas 1955.

She never saw her child alive again.