Convicted sex offender Anthony Lyons has been sent back to prison.

The 53-year-old businessman was jailed for six months and ordered to pay €75,000 to a woman he attacked and sexually assaulted in Dublin nearly four years ago.

The Court of Criminal Appeal today ruled that sentence was unduly lenient and imposed a six-year sentence, with four years suspended.

With remission and time already served, he will spend the next 14 months in jail.

Lyons followed, attacked and sexually assaulted a young woman on Griffith Avenue in Dublin in the early hours of 3 October 2010.

The father-of-four fled the scene when a passerby went to the woman's aid.

He was less than 100m from his home when gardaí, with the victim in the back of the patrol car, caught and arrested him.

He pleaded not guilty and claimed he had been under the influence of cholesterol medicine, but a jury rejected that defence and convicted him.

Judge Desmond Hogan jailed him for six months and directed him to pay the victim €75,000 - money she said she did not want.

The Director of Public Prosecutions appealed the leniency of the sentence and today the Court of Criminal Appeal found the sentence by Judge Hogan unduly lenient.

Mr Justice John Murray said the trial judge had erred in principle by giving undue weight to the mitigating factors.

He also said the subsequent payment of almost €200,000 to the victim in settlement of a civil action was not a relevant mitigating factor.

The victim has welcomed Lyons's return to prison today but criticised the length of time the court proceedings has taken.

In a statement to RTÉ News this afternoon, she said the last four years had been extremely painful and prolonged, as well as extremely traumatic for her and her family.

She said no victim should have to endure court proceedings of such length.

The woman also thanked the two men who came to her aid that night, specifically the man who disturbed Lyons and forced him to flee.

Her family criticised Lyons in a separate statement, saying that at no stage has he shown any remorse for his violent and vicious attack on their daughter.

They stressed he pleaded not guilty and continues to plead not guilty to his "brutal and vile crime".

Both the victim and her family thanked gardaí for their work, the DPP for appealing the original sentence, the Rotunda Hospital and the doctors, counsellors and the Rape Crisis Centre.

Meanwhile, the Legal Director of the Rape Crisis Network has said the long delay seen in the resolution of the case should never happen.

Caroline Counihan said the system should ensure that such an appeal should be heard much earlier.

"I really really hear what the complainant has said about the length of time that it has taken for this to be resolved.

"And that echoes our own daily experience with our clients, and it echoes the findings of our own research.

"Such a long delay should never happen in such a case," she said.

Commenting on the ruling, Ms Counihan said she was very glad that the Court of Criminal Appeal had now given much clearer guidance on where compensation should come in on sentencing.

However, she said we did not have a set of sentencing guidelines for all judges for rape and sexual assault cases, and said her organisation had advocated for years for guidelines.