Lawyers for a care worker twice cleared of the same sex abuse charges have welcomed the ruling that freed him.
Anver Daud Sheikh was twice convicted and twice cleared
Anver Sheikh, 56, from Leicester, was freed after an appeal court quashed for the second time his conviction for offences allegedly committed in 1980.
Mr Sheikh was convicted in 2002 - and again in 2005 - of sex charges against boys at a North Yorks children's home.
The Court of Appeal ruled that Mr Sheikh's latest appeal had succeeded in relation to missing documents.
He was originally jailed for eight years but his conviction for serious sexual assault was overturned in February 2004 by Court of Appeal judges.
At that time he was released on bail, but a retrial was ordered and he faced a jury for a second time.
In January last year Mr Sheikh was convicted again following a trial at Leeds Crown Court.
Lord Justice Hooper, Mr Justice Aikens and Mr Justice Lloyd Jones, sitting in London, announced the reasons for their decision on Tuesday.
They said missing documents - "in particular the staff rota and the personnel records that were likely to be highly relevant to two issues in this case" - were missing.
Lord Justice Hooper said: "In these circumstances we have grave doubts whether a judge who properly analysed the consequences of the missing documents would conclude that the trial was fair."
Commenting on the ruling, Mr Sheikh's solicitor Mark Newby, who is also director of the Historical Abuse Appeal Panel, said: "A line in the sand has been drawn today. Society abhors abuse, we all do.
"But the justice system must search out and convict those for whom there is corroborating evidence against them, not just the unsubstantiated evidence of complainants."