Duffy, 29, whose lead was such that she needed only to finish seventh or better to secure another world gold, won her sixth race of the season to finish with a maximum possible score.

As she rounded the corner to the finishing straight her mask of concentration dissolved into a broad grin and after pushing her sunglasses up she had enough time to take a proferred Bermuda flag from the crowd and offer high fives to fans lining the route to her left before walking through the line to clock 1hr 58min 39sec.

Katie Zaferes of the United States took second place on the day, 55 seconds behind.

Third place went to Britain’s Jess Learmonth, who hung on despite suffering a reported calf strain on the run which left her looking anxiously over her shoulder as she approached the finish line, where she recorded 02:00.57.

Learmonth, who secured her first podium finish in Stockholm last month, led after the swim and was joined by Duffy and Zaferes in a breakaway group on the bike before Duffy raced clear on the 10km run.

Sixth place on the day was enough to give Australia’s Ashleigh Gentle second place overall behind Duffy.

“I am pretty reluctant to ever say you can have a perfect race, but I would say today went just how I wanted it to," said the Bermudan athlete.

"I had a great swim and set myself up perfectly for the bike.

"I tried to play it safe on the bike because there is so much on the line and then on the run I felt pretty strong, so I wanted to go for it.

"Yeah, it was a great day."

Mola, 27, who carried a lead that meant he needed to finish in the top five for a successful defence,  was placed third to become only the second man - after fellow Spaniard Javier Gomez - to successfully defend the title.

The 34-year-old Gomez, five times a world champion, was the only male athlete with realistic chances of overtaking Mola in the season’s finale, where double points were on offer, but he finished one place behind the champion.

Victory on the day went to Vincent Luis of France, who clocked 1hr 51min 26sec to secure his first WTS win of the season, with Norway’s Kristian Blummenfelt passing swathes of runners to take second place, just two seconds behind.

Mola finished eight seconds behind the Norwegian on 01:51.36 to secure Spain’s fifth title in a row, with Gomez taking fourth place in 1:51.41 to earn second place overall.

“It sounds great,” said Mola.

“I can’t describe it with words.

“You are always nervous before a race, no matter what the situation or where you are, I am sure you are going to have those nerves in order to perform well.

“I knew I was in a good situation, I wish I could race every year with these kinds of points going into the Grand Final and this type of situation, but I knew I had to race very well or else it was not going to be easy.

“But it was the title, so that is what I tried to do.”

Gomez, who won the Ironman 70.3 World Championship in Chattanooga last weekend, commented: “I am very pleased with this year, I was focused on different distances and still managed to get the silver medal.”

Britain’s Jonny Brownlee clocked 01.51.52 to finish fifth and sixth in the overall standings.

Brownlee, whose brother Alistair, double Olympic champion, had to cut short his season last month to have hip surgery, had an unfortunate time in his final race of 2017, having to swim without his goggles.

"I had to take them off because I couldn't see where I was going," said the 2012 world champion.

"It was just one of those bad luck days.”