Prince Charles and the Duchess of Cornwall called in at Penfolds' historic Magill Estate during a stop in South Australia – part of a tour to Commonwealth countries to mark Queen Elizabeth II's diamond jubilee.

At the Penfolds vineyard they sipped a glass of ultra-rare 1962 Coonawarra Cabernet Kalimna Shiraz while sampling a selection of South Australian food. Charles reportedly described a risotto prepared by schoolchildren as "frightfully good."

Winemaker Peter Gago told journalists the royal drop was from a batch of only 425 cases, with just a handful of bottles still in existence. He said he was surprised they actually drank it, rather than simply smelling and sipping the wine. "They absolutely loved it," Gago revealed.

It would have been a shame to waste the wine. Produced by pioneer winemaker Max Schubert, the 1962 Coonawarra Cabernet Kalimna Shiraz is generally considered to be one of the greatest-ever Australian red wines. 

As Gago told reporters, "That wine has lovely maturation characters and it's half-a-century old."

Wine critic Tyler Colman, aka Dr. Vino, described tasting the 1962 Bin 60A as the "equivalent of a buzzer beater and a walk off grand slam all in one." Delicate and elegant, it had "aromas of cigar box and dried fruits, a fine tannic structure with a finish that lingers for the whole afternoon."

Australian culinary queen Maggie Beer was responsible for selecting a range of South Australian foods to set before the royal couple during their Penfolds visit.

She chose a 30-kilogram blue-fin tuna from Port Lincoln; Gulf prawns, mussels and oysters; organic vegetables; and locally produced extra-virgin olive oil. In addition, the royal visitors saw South Australian cheeses, heritage pork and beef, free-range chickens, salt-bush mutton, and kangaroo cooked with herbs sourced from Aboriginal communities.

Before the visit began, Beer said: "We'll be showing a glimpse of food from our clean seas and our land, and I'll be telling stories about South Australia and what makes us special here with our Mediterranean climate and extraordinary foods."

Earlier in the day Camilla spoke of her mother's death from osteoporosis as she used the royal couple's Australian tour to highlight a cause close to her heart.

"I watched my mother die in agony from this disease," said the duchess, who is president of Britain's National Osteoporosis Society, during a stop at an Osteoporosis Australia function in Melbourne. "I was determined, when I came to Australia, that I was going to get an osteoporosis reception and I have."

Charles and Camilla began the Australian leg of their tour in the remote Outback town of Longreach on Monday, following a successful visit to Papua New Guinea.

They are due to take in Hobart, Sydney and Canberra before leaving for New Zealand on Saturday.

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