THE one inescapable fact to emerge from the trial and conviction of Roy Whiting is that he was a proven sex offender who should never have been set free.

That he was at liberty to murder Sarah Payne is an indictment of our justice system.

If there is one lesson to be learned from this evil crime it must be that convicted sex offenders who are likely to strike again must not be released into society.

The Government needs to consider the abandonment of fixed-term sentences for sex offenders, and instead introduce indefinite jail sentences. Such punishments would mean predatory paedophiles would not be released from prison until authorities agree they were unlikely to strike again.

Had such safeguards been in place, Roy Whiting would have remained behind bars, and Sarah Payne would have been alive today.

It is because of this inherent flaw in the protection of children that the calls for "Sarah's Law" have gathered momentum. The calls are understandable.

As upholders of the rule of law, we are concerned about public access to the identity of offenders. "Sarah's Law" would tempt people into taking the law into their own hands and resorting to vigilante justice.

We cannot condone such actions.

But equally, we fully understand why every parent would want to know if a convicted paedophile was within their community, and would want him removed from their midst.

We also understand the disgust that Roy Whiting's previous conviction for child sex abuse was not disclosed to the jury.

The striking similarity between that case and the murder of Sarah Payne would have been damning evidence.

However, we share the trial judge's satisfaction that Whiting was tried and convicted on the facts of this murder and this kidnap, and not on his criminal record.

Revulsion of an heinous crime and the overwhelming desire to find the perpetrator must not take precedence over the need to conduct a fair trial.

We must resist the temptation to bolster a weak prosecution case by bringing up previous convictions.

Yesterday's conviction of Roy Whiting for the murder of Sarah Payne is reason to acclaim the strength of our system of trial by jury.

The weakness lies in the system which set him free in the first place.