The Frenchmen clocked a Championship record of 3 hours 33min 11sec, the second fastest time ever behind the 3:32:33 he recorded in winning his third European title in Zurich three years ago.

Henriques bettered her own world record, clocking 4:05:56 in a race that, due to stringent IAAF time guidelines announced when the event was added to the programme last month, involved only seven starters – and produced four finishers.

Later on the same course, China's 21-year-old Jiayu Yang took gold with a late surge in the women's 20km race, clocking a personal best of 1:26:18 in what was her major championship debut to deny Rio 2016 silver medallist Maria Guadalupe Gonzalez of Mexico the title by a single second.

Colombia’s Eider Arevalo won the men's 20km walk title in a national record of 1:18:53 ahead of 18-year-old Sergey Shirobokov, a Russian competing as a neutral athlete, who clocked 1:18:55, with Caio Bonfim taking third place in a Brazilian record of 1:19:04.

Early leader Tom Bosworth, seeking to become the first British race walker to claim a medal in this event at a major championships since Ken Matthews won gold at the 1964 Tokyo Olympics, was distraught after being disqualified from the leading group a little over the halfway mark.

There was an 7.45am start for both 50km races, which took place in bright sunshine on a two kilometres loop up and down The Mall, between St James' and Green Park in central London.

The final lap in the 50km became a victory parade for the mercurial Diniz, who was almost three minutes clear at the halfway point and finished with a winning margin of more than eight minutes over the silver medallist Hirooki Arai of Japan, who clocked 3:41:17, with compatriot Kai Kobayashi claiming bronze in a personal best of 3:41:19.

"It is a lovely Sunday afternoon," said Diniz.

"I know you should never take any decision when you are hot.

"I am still missing one [title] and that is the Olympic one - it would be a nice way to finish in Tokyo [2020]."

For Diniz it has been a long and winding road to global gold – after taking silver at the 2007 IAAF World Championships in Osaka he dropped out of the 2008 Olympics race in Beijing after 30km and was disqualified at the 2011 World Championships in Daegu.

He was also disqualified at London 2012, where he finished eighth, for taking a water bottle outside an official zone.

An operation forced him to miss the last World Championships in Beijing two years, and a stomach upset caused him to faint several times en route at Rio 2016 where he eventually finished eighth.

Perhaps the stars were aligned for the man who comes from Epernay in northern France - Australia’s London 2012 champion Jared Tallent had to pull out of these Championships five days before they started because of a hamstring injury, while the Slovak who won the title in Beijing, and who beat Tallent to the Rio 2016 gold, Matej Tóth, is currently suspended facing a doping charge.

Diniz made the most of the occasion as he grabbed a Tricolore near the end and acknowledged the dense crowds that had congregated for this unusual sporting spectacle.

Meanwhile Ireland's 39-year-old Robert Heffernan, world 50km world champion in 2013, was hinting strongly after finishing eighth that he had just taken part in his last race.

"It's time for me to help the new generation," he said. 

They were still there for the finish of the inaugural women’s race, which, due to stringent IAAF qualification standards, was contested by only seven athletes, one of whom, Erin Talcott of the United States, was disqualified.

Despite her personal disappointment, Talcott commented: "Just like the men have their events that they like, that they’re stronger at, so do I.

"I’m an okay 20 km walker, but I’m a good 50 km walker, and I love the event.

"There are so many women who are so strong.

"Those women deserve the same opportunities and chances the men have."

It turned out to be a good day for veterans as Henriques, 37, dominated a race in which China replicated the Japanese performance in the men’s race by claiming silver and bronze through Hang Yin, who set an Asian record of 4:08:58, and Shuqing Yang, who clocked a personal best of 4:20:49.

It was the first gold at these Championships for a Portuguese woman since Seville in 1997, when Carla Sacramento won the 1500m title.

"My goal was to go under 4 hours and 6 minutes, so I am really happy with this time," said Henriques.

"It felt like at home in London with so many Portuguese fans supporting me.

"I hope that in future we will see more women competing at this distance."

America's Kathleen Burnett was the only other finisher, as her team-mate Susan Randall and Brazil’s Nair Da Rosa failed to finish.

Gonzalez, overtaken in the closing stages of the Rio 2016 women’s 20km race walk by China’s Liu Hong, who finished two seconds clear, experienced déjà vu in London as another Chinese walker, Jiayu Yang, came past her at the last to win by an even closer margin.

The Mexican had tried everything she knew to get clear on the looped course around The Mall after a group of five remained in contention with one lap remaining, and as the finish approached a group of three athletes - Gonzalez, Liu Hong and China’s fastest walker in terms of previous times, Liu Xiuzhi, had broken clear.

The dramatic disqualification of Liu Xiuzhiil 50 metres from the line allowed Italy's Antonella Palmisano to take the bronze medal - Italy's first of the championships - in a lifetime best of 1:26:36.