FORMER priest and St Pius X High School teacher John Sidney Denham's sentencing on 29 child sex abuse charges was abandoned yesterday after he sacked his legal team and made a late bid to plead not guilty to some charges.

The surprise move stunned at least 10 of his alleged victims and family members who were in the court, and prompted Sydney District Court Judge Helen Syme to express "some frustration" at the delay.

Barrister Peter Strain, who appeared on Denham's behalf as a "friend of the court", said Denham had advised him he wanted to reconsider the guilty pleas he entered last year on some of the charges.

Mr Strain asked for the sentencing to be adjourned to prepare a possible application to withdraw the guilty pleas because "I don't know the man. I know nothing about this case."

The application could include Denham waiving his lawyer/client privilege to provide evidence about legal advice he received before entering the guilty pleas, the court was told.

Judge Syme acknowledged the frustration felt by Denham's alleged victims, said the adjournment was needed "in the interest of justice", but told the court she had "no intention of adjourning for six weeks to see what happens when we get back".

The possible withdrawal of some of the guilty pleas made personally by Denham in December was "a matter [that] doesn't happen automatically", she said.

Denham is required to lodge the application with supporting documents by March 19 for a possible withdrawal of plea hearing on March 26.

If the application does not proceed, Judge Syme told the court she would sentence Denham as soon as possible after that date.

If the application proceeds and Denham succeeds in withdrawing his guilty pleas to some of the charges, those matters will go to trial.

Denham was charged with abusing students at St Pius X High School Adamstown in the 1970s and 1980s.

He arrived at the Maitland-Newcastle Catholic Diocese Mayfield parish in 1972 and was moved to Singleton in 1973. He was a teacher at St Pius X from 1975 to 1980.

In December last year he pleaded guilty to 29 charges, including buggery and indecent assault, and asked the court to take into account another 32 offences in sentencing him.

Outside the court one of his alleged victims said he was disappointed the sentencing had not gone ahead, but was "resigned to the long haul" of the legal process.