Children sent to live abroad in the aftermath of World War Two were exposed to sexual violence and other threats during a "fundamentally flawed" Government programme, a report has concluded.
Around 2,000 young people from the UK who were relocated to countries including Australia and New Zealand should now be "offered compensation".
Britain's child migration programmes mainly dealt with people from care or poor backgrounds.
But successive UK governments, which played a "central role" in the policy after the war, "failed to ensure that there were in place sufficient measures to protect children from sexual abuse".
The latest findings were made by the Independent Inquiry into Child Sexual Abuse.
Former Prime Minister Gordon Brown formally apologised on behalf of the Government in 2010 and later gave evidence to the inquiry.
The 162-page document said it was "essential" that all living former migrants - around 2,000 people - are offered compensation promptly.
Around 4,000 children in total were migrated post-war.
The report said: "HMG (Her Majesty's Government) was, over many years, the institution primarily responsible for the post-war child migration programmes."
It went on: "However we have found that post-war child migration was a fundamentally flawed policy and that HMG failed to ensure that there were in place sufficient measures to protect children from sexual abuse (as well as other forms of abuse and neglect)."
The report continued: "HMG has not yet made any financial redress directly to individual former child migrants.
"Most former migrants have died. This means that in many cases HMG has missed its opportunity to offer redress to those who were affected by its failure.
Migrant locked in place known as "the dungeon"
The inquiry heard many harrowing accounts of sexual abuse suffered by British child migrants.
Many witnesses described 'care' regimes which included physical abuse, emotional abuse and neglect, as well as sexual abuse.
Some people described constant hunger, medical neglect and poor education.
In one case, the report described a pet horse being killed in front of around 15 children as a form of "collective punishment for alleged wrongdoing".
And another example recounted a former migrant being locked in a place known as "the dungeon" in one school, where he was left without food or water for days.