Spiegelhalter was speaking at the MRS’s annual conference, Impact 2016, in an insightful and humorous presentation that examined sex and stats.

The first challenge of studying people’s sexual behaviour is defining sex itself, he told delegates. "How can we ask questions of peoples’ behaviour that they might be embarrassed about telling us? One of the problems with sex surveys is that people understand different things by sex."

The issue of defining what sex is came to prominence in the late 1990s when US president Bill Clinton and White House aide Monica Lewinsky were embroiled in a scandal over her performing oral sex on him.

"What was interesting was his definition of sex," Spiegelhalter said. "He claims that he didn’t have sexual relations with her, while she claims that she did have sexual relations with him." There was a vote in the Senate and it found in his favour. Oral sex was not sex.

Spiegelhalter went on to explain how he has devised a star rating system that he expounds on in his recently published book on sex and statistics, Sex By Numbers.

"One of things I do in the book is to crudely give star ratings to data," he said. "If you Google sex stats most of what comes up is nonsensical."

Spiegelhalter awards four stars to surveys "where you can believe the numbers and don’t put margins of error on them". Such statistics include that in 1973, one in 20 16-year-old girls got pregnant

Three-star stats are for what Spiegelhalter considers "reasonably accurate numbers, say up to around 20% up or down".

Internet panels fall into the two-star category for Spiegelhalter, a rating that marks data that "can be used as a very rough ballpark figure, but with details that are unreliable".

But the most derisory rating applies to the specious findings unearthed in magazine surveys and their ilk, which come bottom of Spiegelhalter’s system, scoring just one star.

Spiegelhalter is donating his fee for speaking to charity Karuna, which is dedicating to empowering women in South Asia.