The cover-up by court officials that has given 1,200 convicts a clean record

Hundreds of convicted burglars, muggers and yobs have escaped without a criminal record because of a "systematic cover-up" of court blunders, it emerged last night.

The shocking catalogue of errors includes the failure to record on the Police National Computer the court verdict passed down to 1,200 serious offenders.

It means that, because no official record of their guilt exists, a Criminal Records Bureau check would not flag up their danger to the public, leaving offenders free to get jobs in schools and care homes.

Other revelations from Leeds Magistrates' Court include outstanding warrants being withdrawn for 555 offenders suspected of 1,709 crimes after they failed to turn up in court.

In some instances, criminals already found guilty had their convictions simply "cancelled" when they did not show.

Incredibly, in a handful of cases, lazy court staff could not even be bothered to input the result of hearings and so simply made them up.

This extraordinary "guesswork" - which could have led to the innocent being wrongly labelled guilty - was used in a dozen cases to cover the officials' tracks after they failed to record the original verdict.

Last night, Justice Secretary Jack Straw described the findings as a "lamentable picture of historic failure".

He said staff - only two of whom have been punished - were guilty of a "systematic covering up of errors", and that officials are now desperately trying to bring all records up to date.

But opposition MPs questioned how much ministers knew of the scandal, which was first reported to the Court Service in 2005.

Their concerns centre on the processing of warrants and convictions recorded by the West Yorkshire court dating back to 1980, but mostly between 2001 and 2004.

Inspectors said there had been an "historic failure" to record the outcome of cases.

They discovered that the court's records do not have an accurate result for 3,260 offences - 1,568 of them so serious they should have been immediately entered on to the Police National Computer - relating to 2,206 defendants.

The "worst- case scenario" is that 1,200 defendants have not had the results for 1,568 offences added to the database.

The earliest date of an offence for which a result is not recorded is 1980 and the last is April 2004, the report added.

Crimes not added to the police computer would not be detected by a CRB check, which screens those who are applying for sensitive posts for a criminal past, including sex offences.

Offences where the results are missing include wounding with intent, GBH, possessing ammunition, escape from custody, burglary, robbery, affray, dangerous driving, possessing Class A drugs with intent to supply, and criminal damage.

Inspectors also found that many warrants were withdrawn when an offender was not traced within four months.

Crucially, the decision to stop hunting the suspect was taken by a court official rather than magistrates themselves. Normally, a judge or magistrate must make such decisions.

The failure to keep records up to date also led to the "possibility that an individual may have been imprisoned twice for the same offence", officials admit.

The report, carried out by the Government's four most senior inspectors, claimed some staff had tried to hide their failure accurately to log court convictions by simply guessing what the results were likely to have been.

People found not guilty could therefore have been recorded as having a conviction.

Last night, Greg Mulholland, MP for Leeds North West, called for criminal charges to be brought against those involved.

"The fact that we are talking about legal advisers actually making up results by guesswork must surely mean that we are talking about a criminal offence," he said.

A spokesman for the Ministry of Justice said two senior managers have been disciplined and that an investigation was ongoing.

However, he admitted the two were given final written warnings, rather than being sacked.