At least 8.7 per cent of samples tested were positive, calling into question predictions before London that less than half a per cent of the 10,500 competitors would resort to cheating.
The scientist in charge of drug-testing, Professor David Cowan, of King's College London, also said at the time he believed that figure would be fewer than 50 athletes - "and I think that estimate will be on the high side".
That forecast is close to being proven wildly inaccurate by figures that indicate London was no cleaner than any previous Olympics.
Indeed, 62 results being annulled for drug offences would be the most of any Games unless further retests from Beijing four years earlier lead to more being wiped out there.
The announcement about the re-examination of the London samples came just over a week after it was revealed 31 athletes had tested positive from a fresh analysis of 454 samples from the 2008 Olympics.
Another failure was confirmed on Friday, taking it to 32 on top of the 21 Beijing results that had already been annulled during the last eight years because of doping offences.
The IOC did not divulge whether any of the 23 athletes who failed the London retests had also been among the Beijing 32 and neither did it provide more information about the nationalities of those affected.
The British Olympic Association said last night it had been given no indication any members of Team GB had been among either wave of failures, while it is understood there were no British track and field athletes among them.
In fact, it emerged this week that Britain stood to benefit from the retests in the shape of two additional medals from the 2008 Games after 14 Russian athletes were named among those who produced positive samples eight years on.
It is understood Russians were also caught during the London 2012 reanalysis, the results of which were announced less than seven months after the country was accused by a World Anti-Doping Agency independent commission of having "sabotaged" the event through "state-sponsored" cheating.
Martyn Rooney was part of the 4x400?metres team that could be awarded a bronze medal from Beijing and also competed on home soil four years later.
"It's shame that it's going to be one of the dirtiest Games," he told The Daily Telegraph. "As a fan of the sport, it's disappointing to see that people were still cheating then.
"But if we're catching more people because we're doing better testing and we're closing in on the drugs cheats sooner then I suppose it's not a bad thing, just hopefully more of a deterrent for the future."
Greg Rutherford, who won long-jump gold on Super Saturday at London 2012, added: "It's all well and good getting caught years later, as we've seen from Beijing and London. But we have to see people receive a punishment.
"Obviously, they lose their medals but they've been able to enjoy the plaudits and money that comes from winning Olympic medals.
"There has to be a stronger stance towards those people. Because ultimately they've taken a lot away from people who finished fourth and fifth, even if they managed to be upgraded."
Lord Coe, the architect of London 2012 who is now president of the International Association of Athletics Federations and chairman of the BOA, said: "The London 2012 Games were an amazing event with 10,500 athletes competing across 26 sports.
"Even one cheat in that 10,500 is too many but, using intelligence-based testing, the message is clear to any athlete who believes they may be a little ahead of testing technology at any given moment in their career: we will catch you; we will not stop building profiles or sharing information.
"If today's reanalysis means fewer cheats compete at the Rio 2016 Games then we are clearly moving in the right direction in our mission to protect and promote clean athletes and clean sport."
Thomas Bach, the IOC president, said: "These reanalyses show, once again, our determination in the fight against doping. We want to keep the dopers away from the Olympic Games in Rio de Janeiro.
"This is why we are acting swiftly now. I have already appointed a disciplinary commission, which has the full power to take all the decisions on behalf of the IOC."
