King Charles and Queen Camilla cap a six-day visit to Australia with a community barbecue and a military jamboree aside Sydney's iconic Opera House Tuesday
King Charles and Queen Camilla cap a six-day visit to Australia with a community barbecue and a military jamboree aside Sydney's iconic Opera House Tuesday AFP

King Charles and Queen Camilla cap a six-day visit to Australia with a community barbecue and a military jamboree aside Sydney's iconic Opera House Tuesday.

On the last full day of engagements Down Under, the 75-year-old regent will crisscross the city at a series of events hoping to shore up shaky Australian support for the monarchy.

Rather than bread and circuses, the king will offer antipodean subjects sausage 'sangas' and a navy fleet review in the glistening harbour city.

For lunch, he will attend a community barbecue overseen by MasterChef Australia winner Adam Liaw designed to showcase the "cultural diversity of modern Australia".

Guests will be treated to a game of backyard cricket, henna tattooing and a sheep dog display.

Paramatta, the suburb that will host the event, has large Chinese and Indian communities that traditionally have less affinity for the Britain-based head of state.

Almost 60 percent of Paramatta's population was born outside Australia, according to the latest census figures.

In the afternoon, the king will meet celebrated oncologists Georgina Long and Richard Scolyer as well as cancer patients at the Melanoma Institute Australia.

Thousands of citizens of this sun-baked country get skin cancer every year, prompting Australia's scientists to pioneer a suite of new treatments.

Charles himself was diagnosed with cancer eight months ago and remains in treatment.

His type of cancer has not been publicly disclosed.

In the early evening, Charles and Queen Camilla will embark on what may be the centrepiece of their Australian visit.

The royals will meet members of the public on the Sydney Opera House forecourt before surveying warships gathered in the harbour and witnessing an airforce flyover.

It was at the Opera House in 1983 that the then-prince Charles and a 21-year-old princess Diana greeted thousands of admirers.

It was seemingly a public triumph. But Diana, who stole the show, was later photographed bursting into tears at the event.

Commentators said it was one of the first public signs of tumult in their fairytale marriage. The pair would later separate and divorce.

This time round, a flotilla of guided missile destroyers, helicopter frigates and coastal minehunters have been assembled for the occasion.

And an array of Black Hawk helicopters, Super Hornet and F-35A fighter jets will scream by overhead.

Savvy cruise boat operators had been selling tickets for the event at US$66 per person.

In time for the event, Charles was awarded a spray of military gongs to mark his arrival in Australia.

The one-time trainee jet pilot who crashed an RAF plane in remote northwest Scotland now holds five-star ranks in each of the Australian service branches.

Charles, in addition to being king of the realm, can now call himself field marshal of Australia's army, marshal of its airforce and admiral of the fleet.

On Wednesday, the royal couple depart for Samoa, where they will attend a Commonwealth summit.