Miller, also known as Amy George, lured the young victim into his car after offering to give her a lift home in February this year.

The former butcher, 53, who identifies as a transgender woman and is said to be in the process of transitioning, instead drove the girl to his own house in the Scottish Borders and trapped her in his bedroom.

Miller, who was addressed as a male at the High Court in Edinburgh, then subjected his victim to a series of sexual assaults over the course of the next 27 hours. He also made her watch pornography.

Passing sentence, Lord Arthurson said: "The narrative of your offending in this case which was read out in court on the occasion of your last appearance was frankly nauseating in its level of depravity and criminal deviance."

The judge described the abduction as "brazen and chilling".

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

Lord Arthurson said: "Your intentions were wicked and predatory, and clearly involved a substantial component of planning."

The judge told Miller crimes of this nature were "mercifully rare".

He added: "It is a uniquely appalling crime, striking as it does at the heart of family life and indeed the very fabric of our society.

"It is a crime that brings justifiable universal opprobrium upon the offender and which rightly merits the severest level of punishment properly available to our courts.

"It is what the public has every right to expect, and today it is what you shall receive."

As well as the 20-year jail term, Miller will also be supervised for eight years upon his release from prison. He has been placed on the sex offenders' register indefinitely.

Defence advocate Victoria Dow told the court that Miller "recognises and feels the horror of his conduct" and was said to feel an "enduring sense of shame".

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

The High Court in Edinburgh was previously told 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.

Lord Arthurson previously described the "abhorrent crimes" as the "realisation of every parent's worst nightmare".

Miller had pleaded guilty to abduction, sexual assault, intentionally causing a child to look at a sexual image, and possessing 242 indecent images of children.

Miller and the victim were not known to each other.

The girl told officers that she accepted a lift because she believed Miller - who was wearing women's clothing - was non-threatening.

During a police interview, Miller told detectives he did not abduct the girl and that it was "all a mistake", saying he stopped to offer her a lift because she looked "freezing".

He said he put her in his bed with him because it was a "motherly thing", and admitted he should have called the police and should "never have gotten into this situation".

Lord Arthurson said: "Your victim repeatedly asked to be allowed to go home.

"You told her that you intended to keep her for a week and on another occasion that you were not going to let her leave as she was your 'new family'."

A background report assessed Miller as a medium risk of reoffending.

The judge added: "On a number of occasions the risk assessor reports that you referred to the abduction as a 'game'.

"In terms, however, of the ending of the abduction, you told the reporter that you 'went into business mode trying to think of a solution', and that you needed time to formulate your 'plan'.

"Thankfully your victim took that matter out of your hands, by way of her call to the emergency services."

Following Miller's arrest, three laptops were seized from his property and a total of 242 indecent images of children were found, most of which were of the lowest category.

His internet history was also accessed, showing his searches for indecent images.

Lord Arthurson said: "In the risk assessment report the author posits a future risk scenario in similar circumstances.

"The author expresses the view that while she doubted that fatal harm would be your initial intent, this could become a more likely occurrence with a prolonged abduction in circumstances in which the child in such a future scenario, just as in the present case, would be readily able to identify you in the event of her being released or making an escape."

The local butcher shop Miller once owned - which had been closed before the abduction - was boarded up by police at the time.

Lord Arthurson said: "The suffering of your victim and her family at your hands has been incalculable and life changing.

"The trauma further inflicted by you upon her local community and the wider public is also immeasurable."

Miller was remanded into the male prison estate after pleading guilty in May.

It followed new guidelines for trans prisoners who commit sexual offences following a public outcry over the Isla Bryson case.

Double rapist Bryson was initially placed in an all-female prison before being moved to a jail with male inmates.

Bryson, who attacked two women while identifying as a man, decided to transition while awaiting trial, which provoked outrage among campaigners.

At the time of Miller's guilty pleas, First Minister Humza Yousaf told Sky News that he could not say whether he would be moved to a women's jail after being sentenced.

Speaking to the media at Holyrood, he added: "The Scottish Prison Service has protocols in place.

"Those have recently been updated in relation to some other very well-publicised cases, and therefore I'm very confident in any risk assessment SPS makes in this regard."