Burling steered the Kiwis' foiling 50-foot catamaran to victory in the podium race of the Great Britain Sail Grand Prix on Sunday, beating Slingsby, his rival from across the Tasman Sea.

Victory ended Team Australia's five-regatta winning streak spanning two seasons. Denmark's Nicolai Sehested finished third in his first SailGP podium race.

Slingsby has led the Aussies to consecutive season championships and the US$1million prize, and had won seven of the last eight regattas.

Before the second day of the regatta began, Kate Middleton, the Duchess of Cambridge, steered the British catamaran to victory (with British sailing star Sir Ben Ainslie at her side) past the Kiwis in a friendly Commonwealth race.

But Burling won the race that really mattered and jumped into third place in the season standings of the nine-boat fleet in tech tycoon Larry Ellison's global league.

Team Australia remains first and Britain second.

Burling and Blair Tuke, two of the world's most accomplished sailors, joined SailGP for Season 2 with high expectations but struggled and finished fifth in the season standings.

"I think a lot of people would have expected this of us by now and it's great to have put together a good weekend and put in such a dominant performance," Burling said.

"We have been working really hard to improve and I think we truly proved that today."

Burling and Tuke have led Emirates Team New Zealand to consecutive victories in the America's Cup and won three Olympic medals, including one gold.

That's why it was a mystery why they struggled after joining SailGP, considering that the foiling 50-foot catamarans are an updated version of what they sailed to beat defending champion Oracle Team USA in the 2017 America's Cup.

The Kiwis had a six-point lead after going 2-2-1 in Saturday's fleet races and then went 5-1 in the final two fleet races Sunday to reach the podium race.

After Burling won the start, all three boats fell off their foils in light wind. Sehested got his cat foiling again but Burling swooped into the lead at the third gate and sailed off for the win.

"It's been a big push to get to this point but I'm really pleased with the way we've been sailing and improving," he said.

Ainslie, the most-decorated sailor in Olympic history and a former America's Cup champion, missed a spot in the final race in home waters by a slim margin.

The British skipper was penalised for a close cross against Australia just before the finish of the fifth fleet race. Ainslie said it was a "bad call."

The Aussies' regatta nearly ended with a broken rudder in the fourth fleet race but it was quickly repaired.

"We are not disappointed at all," said Slingsby, an Olympic gold medallist and former America's Cup champion.

"Actually, we are ecstatic about coming second in this event. It was just a really tough day for us."

Australian Associated Press