The French world record holder, one of the great figures of race walking, produced the second fastest walk in history, 3 hours 33 minutes 12 seconds -- a time only he has bettered -- with one of the performances of the entire World Championships.
Diniz was so dominant en route to his long-awaited first global title that he lapped nearly all the 43-strong field over the 2km looped circuit on The Mall, finishing less than a minute adrift of his three-year-old world record of 3:32:33.
He was even able to take a swift comfort break when leading in the first 15 minutes before rejoining the race and destroying his opponents over the 25 laps between Admiralty Arch and Buckingham Palace.
A great showman, father of two Diniz was even able to smile and wave to the crowds lining the course well before the finish as he landed a third gold of the championships for France.
He blew kisses towards Buckingham Palace on the last circuit, turning it into a glorified lap of honour, and approached the line while making a scarf out of a tricolour he had grabbed from the crowd before then hoisting it aloft to celebrate his new championship record.
He had only one moment of concern when he received a red card for an infringement at about the 20km mark. "I started having doubts but in training, we have been doing lots of changes of rhythms, so I just kept going.
"I got a card too and I thought 'I just must not mess this up.' I just concentrated completely on my technique.
"Last night I kept away from watching the athletics on TV because I did not want to get too excited. I went to bed at nine because I knew it was going to be my day!"
His eight-minute gap over his two distant Japanese pursuers, silver medallist Hirooki Arai (3:41:17) and bronze medallist Kai Kobayashi (3:41:19), was by far the biggest ever recorded in the championships.
Diniz became the oldest male world champion in any event, surpassing another walker, 37-year-old Veniamin Soldatenko. The Soviet athlete won a specially-staged 50km event in Malmo in 1976, seven years before Helsinki staged the first global championships.
Belarussian Ellina Zvereva holds the overall record of being the oldest world champion, having won the women's discus in 2001 at the age of 40.
Diniz's triumph, the first ever in race walking by a Frenchman, came a year after his heartbreak in the Rio Olympic final when he led by nearly two minutes before he collapsed at 37km with heatstroke, dehydration and gastric problems.
He was then hailed as a hero as he got up, insisted on continuing and, incredibly, finished the race in eighth place.
When Diniz competed on this same course on the Mall during the 2012 Olympics, he had been forced to pull out during the race.
His familiar all-or-nothing approach had seen the three-time European champion Diniz miss out in five previous global championships but for a man famed for being a wine-making expert, this was a champagne moment.
Would it not perhaps be the perfect time to retire on a high, he was asked. "It is a lovely Sunday afternoon. I know you should never take any decision when you are hot," he smiled.
"I am still missing one title and that is the Olympic one. It would be a nice way to finish in Tokyo."
(Reporting by Ian Chadband, editing by Pritha Sarkar)
