SA taxpayers funded Zara and Mike Tindall’s visit to South Australia for the Valo Adelaide 500

After refusing to say how much was outlaid to bring Sam Smith to Adelaide, the government also remains tight-lipped over what was paid for a royal pair to attend the rebooted Adelaide 500.

Minor members of one of the world’s richest families were paid to attend the rebooted Valo Adelaide 500 last year, but the state government is refusing to divulge how much taxpayer money was spent to bring them to the car race, citing “commercial-in-confidence’’.

Zara Tindall, the granddaughter of the late Queen Elizabeth II and niece of King Charles III, and her husband Mike Tindall were brought to Adelaide for the race, with a government spokesperson for Tourism Minister Zoe Bettison saying their presence “helped contribute towards a successful Adelaide 500’’.

“Contractual details are commercial-in-confidence,’’ the spokesperson said.

The state government’s refusal to outline how much was spent on the junket for the royals, follows its unwillingness to detail how much it outlaid to bring British singer Sam Smith to Adelaide to entertain a hand-picked audience of 300 people at the d’Arenberg Cube at McLaren Vale last week.

Zara and Mike Tindall at the Adelaide 500 track.

A different government spokesperson would only say the Smith concert cost “well south’’ of a million dollars but refused to define what that meant.

In a statement, the spokesperson justified the splurge on the Tindalls: “Zara Tindall is a prominent member of the royal family and Mike Tindall has a social media reach of 586,000 people.

“They were in Australia working with other partners which helped reduce the cost of bringing them to Adelaide.’’

The spokesperson estimated the Tindall trip gave exposure to SA “worth hundreds of thousands of dollars’’ without explaining how that figure was calculated.

Zara Tindall wearing Paolo Sebastian, with Adelaide designer Paul Vasileff on December 2. Picture: Matt Loxton

Respected financial magazine Forbes has estimated the royal family’s wealth at around $40 billion, mainly built on its extensive property portfolio.

Zara Tindall, who runs a jewellery company, the daughter of Princess Anne, is estimated to be worth around $30 million.

The government spokesperson said the Tindalls visited, as did Sam Smith, the Star of Greece and d’Arenberg. They also did various TV and radio interviews.

She also said the royal had been “dressed’’ by South Australian designers during her public appearances.