On a squally July afternoon of intermittent drizzle the unheralded Lachie Stewart outsprinted Australia's iconic multiple world record-breaker Ron Clarke to win the 10,000 metres title. Running more than 20 seconds faster than ever before, Stewart set a Games record, and a Scottish native best of 28min 11.8sec which still endures.
Even today that victory remains almost beyond comprehension. Clarke had set 19 world records; he was the Haile Gebrselassie or Kenenisa Bekele of his era. He broke 12 in 44 days alone, including being the first man under 13 minutes for 5000m, and first inside 28 for 10k.
The Meadowbank field included Kenya's defending champion Naftali Temu, who had relegated Clarke to second in Kingston four years earlier (and was the Olympic marathon champion); England's UK record-holder Dick Taylor; Alan Rushmer, the Commonwealth three-mile bronze medallist behind Clarke in 1966; and Canada's Jerome Drayton who had won the Fukuoka marathon seven months earlier.
Stewart, 27 at the time, was struggling for top-10 status in Britain and many on the start line were faster. Clarke had held the world best for five years and Stewart, ranked 33rd in the world the previous year, was 47 seconds behind him.
Clarke was already a legend, having lit the Melbourne Olympic flame at 19 but, for all his records, he lacked a sprint finish. He tried everything. On the 19th of the 25 laps, he put in a lung-searing 63-second lap, dropping everyone bar Taylor and Stewart and, on the final bend, he opened a gap . . .
Clarke himself takes up the story, as he related in The Herald's exclusive interview: "I'd raced Lachie a few times and he hadn't been in contention. I knew I wasn't running well, and that there were a few guys who were quite competent and could beat me.
"But when I was able to break them, and got round the last lap, with about 200 metres to go the crowd went wild. And I thought, 'What a wonderful crowd, this Scottish crowd. What a wonderful reception they're giving me'."
As he recalls this, Clarke just can't suppress a throaty self-deprecatory guffaw. "I really, honestly believed they were cheering for me until I heard these little footsteps coming up, and I looked under my right arm. I saw Lachie's feet and got the surprise of my life as I realised all the cheers were for Lachie, who was catching me!"
Stewart, from Dumbarton, cruised into history. Clarke had to settle for his fourth Commonwealth silver. He never did win a major championship gold, yet, in one of sport's most heart-warming gestures, he was given one by Emil Zatopek.
The Czech, who uniquely won the 5k, 10k and marathon at the 1952 Olympics in Helsinki so respected Clarke, who tore his heart apart at the altitude Olympics in Mexico, that he gave him one of those three medals.
An accountant, author, and environmentalist with wide business interests, Clarke conceived and built the Runaway Bay sports facility on Australia's Gold Coast used by Team GB before the Sydney Olympics. He then moved into politics.
Now "completely retired", Clarke will be 77 next week. He lives on the beach on the Gold Coast, which will host the 2018 Commonwealth Games. Clarke was mayor and brokered their right to follow Glasgow, but says the success of the bid was down to Kip Keino, the Kenyan who had denied him gold in Kingston nearly 47 years ago.
"Hambantota [in Sri Lanka] was a very big threat," Clarke said. "We got it because Kip was so influential. All the African delegates were there and Kip swung it our way. We made it by just a few votes."
Clarke lost his daughter and, with her, his motivation. "I decided not to stand for a third four-year term as mayor. I've had nothing to do with the Games since."
He fears Glasgow and his home city must fight to re-establish the Games brand. Gold Coast's funding is less certain than that for 2014. "There is a complete lack of knowledge about staging the event among the organising committee, and no real enthusiasm for it from government," Clarke said. "If they were able to do so politically, the state and federal governments would pull out of it in the blink of an eye.
"The crunch will come when the big money starts to be paid out, together with difficulties there will be in securing major sponsors and possibly much revenue from TV rights. This will depend on just how many of the top-line athletes can be bothered to participate; the event has been losing prestige over the last decade or so."
Clarke adds that Queensland's premier "has no real enthusiasm for sport". When I express surprise at this departure from a perceived national stereotype, Clarke says this has faded. It's a warning to Scotland how legacy can be squandered.
"The sports minister is pretty low down the pecking order," he said. "Sport was used for political purposes and the minister never had much authority. The job was usually thrown to a junior minister too dumb to do anything else."
Clarke also criticises the Australian Institute of Sport, a model adopted and adapted by the UK, with only limited success. "It has never produced a good track and field athlete. England has done it better," he said."I'm not keen on national sport being regimented, almost like an army, developing coaches and kids as they come through.
"There is too much emphasis on the importance of coaches. It is all about the kids and their enthusiasm. I was completely self-coached. I did not have time to mess around, be psychoanalysed, and work out schedules. We just went out and ran."
He denies ever feeling pressure, other than a need to improve himself, which was compromised by heart damage which required surgery after Mexico City. "I just remember trying to get to the finish. It was a long, long straight, it was like one of those nightmares: going towards something and never reaching it."
Clarke's Olympic bronze, won in Tokyo in 1964, was scant reward for one who so peerlessly graced his sport. It prompted a wonderful gesture by Zatopek as Clarke was leaving Prague: "He came on to the plane with me and had a little parcel wrapped in brown paper tied with string. I had the front seat and he handed it to me as we said goodbye.
"I didn't know whether I was smuggling contraband or whatever. I thought I'd better wait until I was through customs in England before I opened it, and if something was discovered I could say I knew nothing about it: that it was just something a friend gave to me. But I lost my nerve while we were doing that interminable taxi-ing round Heathrow and I had a look.
"I held Zatopek in very high esteem. Emotionally it's pretty hard to describe: a phenomenal thing. It keeps on coming back: why he decided to give it to me. There must have been some sort of respect there, or recognition for what I'd done and how frustrated I'd become by the series of things that occurred."
Clarke received the Order of Australia and MBE from the Queen, but treasures this medal above all. "I was just incredibly honoured, and it was a story I thought should be shared," he said. "I considered keeping it private but thought the internationalism it represented and the mutual respect that people from different eras can have was such that it should be shared. So I put the medal with a little story about it in the Gold Coast Sports Hall of Fame. I think that's the best place for it."
He asks if I talk to Lachie (which I do). "Tell him I bitterly resent what he did in Edinburgh!" His sniggering laugh echoes down the line, and grows to another throaty guffaw.