Judge Susan Tapping described Davies' claim that his victims were lying as "nothing more than the wriggling of a cowardly man unable to accept that the past had caught up with him".
She said the victims had found the experience of giving evidence "embarrassing and intrusive", and praised their "total integrity".
She told Davies: "Their courage both individually and together shone through in this courtroom. I hope this light will ease their burdens because none of this was their fault.
"You are the one who must now face your day of reckoning. Maybe you thought you were safe from justice half way around the world, but you were not."
The former miner, who also served with the Royal Engineers and the Royal Dragoons, moved to Australia in 1974.
"You left behind confused and damaged adults and children who grew up with the shadow of what you had done to them haunting them all their lives," Judge Tapping said. She added that his crimes were "utterly depraved".
Davies was confronted by two of his victims in 2008 while they were on holiday in Australia. A third victim later came forward to police, who found the fourth woman after an investigation was launched.
He was arrested last July at his adopted home of Wanneroo on Australia's west coast and extradited in September last year.
He was found guilty of two charges of child rape, two charges of attempted rape, eight counts of indecent assault and one count of indecency with a child.
He was cleared of one charge of child rape and one charge of attempted rape.
During the trial, prosecutor Hanna Llewellyn-Waters said Davies "preyed on the innocence" of the four girls.
"You relied on their fear that they would not be believed and told them that they would be taken away from everything they loved," she added.