Parkinson took his case to the Court of Appeal, which issued its decision on Monday.
Although Parkinson did not deny his offending, he wanted his sentence reduced.
His lawyer said the sentencing judge started too high compared with similar cases and over-egged the offending, and also failed to make a proper discount for mitigating features.
The Crown emphasised the predatory, premeditated and repetitive method of Parkinson’s offending.
In the appeal decision, Justice Brendan Brown said the sentencing judge did recognise Parkinson’s attempts to get help for mental health problems and violence he suffered as a child.
Parkinson used alcohol to deal with emotional problems and recognised he had inappropriate sexual thoughts about children.
Brown said the sentencing judge should have given a lower sentence to take into account Parkinson’s childhood trauma, efforts to seek help and genuine remorse.