Andrew Miller, also known as Amy George, launched a legal bid last October to challenge the length of his 20-year jail term.

Former butcher Miller, who identifies as a transgender woman and is said to be in the process of transitioning, lured the young victim into his car after offering to give her a lift home in February last year.

Miller, 54, instead drove the girl to his own house in the Scottish Borders and trapped her in his bedroom.

He then subjected his victim to a series of sexual assaults over the course of the next 27 hours. He also made her watch pornography.

Miller was addressed as a male at the High Court in Edinburgh when he was sentenced to two decades behind bars and told he would be supervised for a further eight years upon his release.

He was also placed on the sex offenders' register indefinitely.

Appeal judges will now consider if the custodial sentence was "excessive" and placed "too much weight" on his transgender identity, with an "insufficient discount" for an early guilty plea.

On Friday, the appeal court in Edinburgh heard that Miller had lived as a woman for six years prior to the offence and is now supporting other trans prisoners.

Defence advocate Victoria Dow said that after being jailed, Miller was moved to an enhanced unit in Ratho prison, Edinburgh, as he was "trusted", and "wants to understand why he committed the offence".

Ms Dow said: "The 28-year sentence was excessive having regard to the overall circumstances. Nothing I say should be considered to be minimising the offence. Clearly a substantial sentence was appropriate."

She said Miller lived as a woman "for many years", and his "transgender identity had been a factor throughout his life".

She added: "Too much weight has been attached to that factor. It is clear the appellant has experienced psychological difficulties throughout his life. This is his first offence for such a serious matter.

"Prior to the offence he was struggling to cope with a number of factors in his life. He was soothed by the feeling of control.

"No criminal justice social work report was carried out. There simply wasn't one. The headline sentence was excessive. It is submitted in this case that the discount was insufficient."

Ms Dow claimed there were long periods of Miller's life where he did not cause any harm.

She added: "He is not a persistent offender."

Miller pleaded guilty last May to abduction, sexual assault, watching pornography in the presence of a child under the age of 13, and possessing 242 indecent images of children.

A judge described the "abhorrent crimes" as the "realisation of every parent's worst nightmare".

Passing sentence in October, Lord Arthurson said it was "frankly nauseating in its level of depravity and criminal deviance".

The judge described the abduction as "brazen and chilling" and branded Miller's intentions as "wicked and predatory".

He added that Miller being dressed as a woman was an aggravating factor as he doubted that the girl would have got into the car if Miller had presented as a man.

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The court heard the girl was only able to escape after Miller fell asleep on the second night of her ordeal.

She tipped over a glass of water and turned on the bedroom light in an attempt to wake him, but he did not rouse. She then found his landline and raised the alarm.

Police arrived at his home within a matter of minutes.

Officers found Miller wearing a bra with silicone breasts, women's underwear and tights.

Ms Dow previously said that Miller recognised "the horror of his conduct" and felt an "enduring sense of shame".

Miller was also said to have expressed concern over how his behaviour would affect the wider trans community.

A written decision on the appeal bid will be issued at a later date.