Stephen Bower, aged 56, was jailed in July last year for indecent assault, indecency with a child and five counts of rape.
He repeatedly abused two boy and two girls for years, with his offending beginning in the 1970s.
Bower, of Derby Road, Chesterfield, was prosecuted when one of his victims used her mobile phone to record him admitting his crimes.
The judge who sentenced him at Derby Crown Court said Bower’s victims had gone through a ‘heartbreaking’ ordeal.
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“I hope you can put your lives back together again,” he told them.
“No one could fail to be moved by the suffering they have had to endure for years.”
But Bower, who claimed to have no memory of the crimes, challenged his sentence at London’s Appeal Court, where it was reduced.
Bower’s barrister, Rachel Harrison, accepted the gravity of his crimes and said it was ‘horrendous offending’ but successfully argued for three of his indecency convictions to be overturned, due to mis-drafting of the charges.
The sentence was reduced to 22 years.