Victoria Cross recipient Ben Roberts-Smith has been stopped from attending the march-out parade of a slain SAS comrade's son who has followed his late father into military service.

The accused war criminal had applied to have his bail varied so he could watch Henry Diddams graduate from the School of Infantry at Singleton in the NSW Hunter Valley next week. 

Henry's father, Sergeant Blaine Diddams, received the Medal for Gallantry in Afghanistan and was killed in an engagement with insurgents in July 2012.

Roberts-Smith has remained close to Diddams' widow Toni-Ann, daughter Elle-Lou, and Henry, accompanying the siblings to Anzac Day ceremonies when they were children.

He sought permission to help celebrate Henry's completion of his initial infantry training at his June 26 march-out parade at Lone Pine Barracks and a graduation function in Newcastle that evening. 

But after a hearing in Sydney's Downing Centre Local Court on Tuesday, Judge Susan Horan refused to allow Roberts-Smith to attend either event.

Judge Horan expressed particular concern Roberts-Smith might come into contact with another former SAS member who served in Afghanistan at the parade or subsequent gathering.

Simon Buchen SC, for the Commonwealth DPP, had not opposed Roberts-Smith going to the march-out parade but objected to him taking part in the later event.

Mr Buchen described that celebration as an 'uncontrolled social function', where the number of attendees had been only vaguely estimated and alcohol was likely to be present.

Judge Horan recognised Roberts-Smith's close relationship with Henry Diddams and his family. She also accepted Roberts-Smith wished to show support for Henry and was proud of his achievements. 

But she was not prepared to allow for the possibility of Roberts-Smith coming into contact and interacting with one of his former comrades at the parade or graduation function.

Judge Horan did vary Roberts-Smith's bail so he could attend the opening of the new Anzac Hall and Anzac Atrium at the Australian War Memorial in Canberra on June 23.

The new Anzac Hall commemorates Australia's wartime commitments to the Middle East, Afghanistan and peacekeeping operations, and features Roberts-Smith's VC and uniform. 

Roberts-Smith, who also holds the Medal for Gallantry, had been invited to the opening as one of Australia's four living VC recipients.

Judge Horan found that ceremony was a formal official ceremony which differed from the private Diddams graduation function or march out parade, which could be watched via livestream.

Roberts-Smith, whose bail conditions require him to report three times a week to a police station in NSW, is also seeking to move from the Gold Coast to Brisbane. 

Mr Buchen said the CDPP would not oppose Roberts-Smith changing residence but would resist his application to be allowed to report to Queensland police.

Apart from the reporting condition, Roberts-Smith's bail prevents him from leaving Queensland except to meet his lawyers in Perth, and to travel to Sydney for the same reason or to attend court or medical appointments.

Australia's most decorated living soldier was arrested by the Australian Federal Police on April 7 as the 47-year-old prepared to get off a Qantas flight from Brisbane at Sydney Airport.

Despite having repeatedly offered to present himself to police if they intended to arrest him, he was taken into custody in front of his partner Sarah Matulin and twin 15-year-old daughters.

The day trip to Sydney had been a school holiday treat for the girls and everyone in the group had a return ticket to Brisbane.

Roberts-Smith was charged that day with five counts of 'war crime - murder' allegedly committed in Afghanistan's Uruzgan Province between 2009 and 2012.

He is accused of shooting dead one unarmed Afghan detainee, jointly murdering another with a fellow SAS soldier, and ordering subordinates to execute three more.

Roberts-Smith, who has always denied committing war crimes, was first accused of killing Afghan prisoners in a series of reports published in 2018 by Nine newspapers.

He sued Nine for defamation in the Federal Court and in June 2023 Justice Anthony Besanko found the publisher's allegations were substantially true on the balance of probabilities.

A Nine Network television crew was at Sydney Airport to film Roberts-Smith's arrest but no other media were present.

The AFP and the Office of the Special Investigator, which examines war crimes allegations from Afghanistan, have referred that apparent leak to the National Anti-Corruption Commission.

AFP Commissioner Krissy Barrett told a Senate estimates hearing late last month: 'I am not just disappointed the media outlet was there, but I am determined to find out how they knew of the arrest.'

'This could be an unauthorised disclosure and in my view anyone who disclosed that information should face consequences,' she said.

'I have no evidence to suggest the AFP provided information to the media about the date or details of the arrest.'

Ms Barrett said Roberts-Smith was taken into custody at the airport for operational reasons and any offer to present himself to police had been 'unviable'.

A panel accompanying the display of Roberts-Smith's uniform at the Australian War Memorial was altered in the days after his arrest to reflect his present circumstances.

That panel now states: 'In April 2026, Roberts-Smith was charged with five counts of the war crime of murder. The legal process is ongoing.'