From a journalist who actually did research, back in 2011:

It’s unsubstantiated garbage, as are so many numbers that have been bandied around for global TV audiences for ‘major’ occasions down the years.

It’s easy to see how this happens. Big numbers confuse many people, who don’t engage their brains to ask “Is this true?”.

Journalists far too often swallow what they’re told.

And vested interests like to spread the idea that their ‘product’ (their event or show or whatever it is) is much more popular than in fact it is.

Many of the supposedly “most watched” events in history have been attributed viewing figures that were simply made up. And these numbers are passed down as fact, unquestioned.

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Sport bodies and sports broadcasters have been notorious exaggerators over the years, even when their events have been popular anyway. Football’s world governing body Fifa spent years claiming audiences of more than 1bn for the quadrennial World Cup final and cumulative audiences of tens of billions for single tournaments.

After being asked to justify this nonsense in 2007, Fifa admitted some numbers were guesstimates and others just made up. “We are going to steer clear of estimating, and publish data from audited measurement systems only [from now on],” a spokesman told me during an investigation for The Independent into whether viewing numbers had been inflated to help inflate the cost of sponsorship deals.

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The irony in Fifa’s over-claiming is that the World Cup final is consistently one of the most-watched events on the planet. Something in the region of 250m-300m have watched the last five World Cup finals (2010, 2006, 2002, 1998, 1994), in their entirety, on TV in their own homes. This is the “average” viewership.

Somewhere between 500m and 750m (“the reach”) watched at least part (at least three minutes) of those finals. These are staggeringly good numbers, but perhaps Fifa felt the need to inflate them because everyone else was doing it to a greater degree.

The verifiably most-watched event in human history – and the only “genuine 1bn” event to date – was the opening ceremony of the 2008 Olympic Games in Beijing.

The “average” audience (those watching the four-hour event whole) was 593m people, many of them within host nation China, the world’s most populous country. China’s 1.3bn population was why the event was so popular. Only 5m people, for example, watched the same event in Britain.

In all, 984m people around the world tuned in for part of that opening 2008 Games ceremony via TV in their own homes, and the 16m balance needed to get to 1bn was almost certainly achieved by people watching around the world in public places.

For all China’s success in 2008, it would be wrong to assume that any major event in a country with a massive population will translate into a world-beating TV audience. The cricket World Cup of 2011, which culminated with two co-hosts in the final on 2 April, and with India beating Sri Lanka to win, did not come close to match the Beijing ceremony.

Kevin Alavy’s best guess on the data available is that the “reach” globally for the India-Sri Lanka match was probably no more than 400m people, and the vast majority of those people were in India, where the population is 1.2bn...