A man jailed for five years for serious sexual assault has won an appeal against both his conviction and his sentence.

While Kristopher Gibbons, 22, was convicted of serious sexual assault, the Court of Appeal ruled that he should have instead been convicted on the lesser charge of sexual assault.

The Crown had alleged that Gibbons was one of several men who plied a 14-year-old girl with alcohol on July 27, 2013, before sexually assaulting her. Several young men were charged in connection to the incident, but Gibbons alone was convicted. During the Supreme Court trial, the complainant said she was dizzy from the alcohol and was crying during the attack, which ended only after she forced her body to the ground.

Gibbons admitted that he had sexual contact with the girl on the night of the incident, but otherwise denied her version of events. He told the court that none of the other defendants were present when the sexual activity took place, that the complainant was not drunk and at no point did he use force. The jury had been told that if they found Gibbons had alone been involved in the incident, he should be convicted of “simple” sexual assault, while if he had been involved with others he should be convicted of the more serious offence.

However, the jury cleared all of Gibbons’s co-defendants and found him guilty of serious sexual assault.

The defendant subsequently launched an appeal against both his conviction and his sentence.

In a written ruling released by the Court of Appeal yesterday, the panel stated that it had found the serious sexual assault conviction “unsafe” and substituted a conviction for sexual assault.

“The warrant of commitment records that the appellant was convicted of sexual assault rather than serious sexual assault,” the ruling states. “In truth, the jury returned a verdict of serious sexual assault and this was never altered by the court, nor could it have been.

“What should have happened is that the judge should not have accepted the verdict and should have reminded the jury that serious sexual assault could only be committed by the appellant if it was committed by the appellant with another person. There are two possibilities — either the jury overlooked the judge’s direction that serious sexual assault could not be committed by one person alone or they concluded it was committed with one or more of the others unnamed but referred to in the indictment.”

The ruling also stated that before the trial began, Gibbons had offered to plead guilty to “simple” sexual assault on the basis of his version of events, but the Crown did not accept that plea. The Appeal Judges wrote that while prosecutors should not be criticised for not accepting the offer as the nature of their case was very different than the appellants, the offer and verdict meant that Gibbons was entitled to some degree of discount on sentence.

They wrote that had he been tried alone for the offence he admitted, he would have been tried in Magistrates’ Court where sentencing guidelines would have suggested a sentencing range of between one year and 30 months, with a starting point of two years.

“Five years was manifestly excessive on the facts on which the appellant had to be sentenced,” the ruling said. “We would allow the appeal against sentence and substitute a sentence of two years imprisonment. The one year’s probation to follow will remain undisturbed.”