The bodies of about 400 children are believed to be buried in a mass grave in Lanarkshire, southern Scotland, following a discovery made by BBC.
The children were all residents of a care home run by Catholic nuns.
At least 400 children are thought to be buried in a section of St Mary’s Cemetery in Lanark.
The Daughters of Charity of St Vincent de Paul, which ran the home, refused to comment on the findings.
The research by the File on 4 programme in conjunction with theSunday Post newspaper focused on Smyllum Park Orphanage in Lanark.
It opened in 1864 and provided care for orphans or children from broken homes. It closed in 1981, having looked after 11,600 children.
A burial plot, containing the bodies of a number of children, was uncovered by two former residents of Smyllum in 2003.
Frank Docherty and Jim Kane discovered an overgrown, unmarked section of St Mary’s Cemetery during their efforts to reveal physical abuse which they said many former residents had suffered.
In 2004, the campaigners said the Daughters of Charity told them their records suggested that children had been buried in 158 compartments in the graveyard.
Frank and Jim, who both died earlier this year, believed however, that the numbers were far higher as the nuns had indicated their records were incomplete.
The investigation by File on 4 and the Sunday Post indicates they were right; at least 400 children are understood to be buried in the plot.
“Oh my God, I’ve got goose pimples. It’s shocking,” said Frank Docherty’s widow, Janet.
“He had been trying for years to find a figure and he didn’t get anywhere. That’s unbelievable.”
The death records indicate that most of the children died of natural causes, from diseases common at the time such as TB, pneumonia and pleurisy.
Analysis of the records show that a third of those who died were aged five or under.
Very few of those who died, 24 in total, were aged over 15, and most of the deaths occurred between 1870 and 1930.