The judge said that the experience of being locked in a windowless room in "appalling conditions" had taken a physical and psychological toll on the child victim.
Doctors who examined the boy said he was underweight and below average height for his age, and treated him for anaemia.
But Judge Norman Wright said that while the physical effects have been remedied, the psychological harm "will be unknown".
"It is bound, in my judgment, to be profound," he said.
More top news
The National Lottery is upping the number of balls from 49 to 59, a move statisticians point out will make hitting the jackpot harder.
The Tory peer and former Marks & Spencer chief has been named as chairman of the 'In Campaign'.
Delicately worded memo by then press chief from 1985 is among cache of newly released documents from former PM's private files.