Boris Johnson doesn’t know how many kids were born under his watch

In an interview with the Sunday Times today, Boris Johnson predicted that “Romance will bloom across the whole nation once we get Brexit done”, claiming that “There was [a baby boom] after the Olympics, as I prophesied in a speech in 2012, it was quite amazing. There was a big baby boom.”

Now we cannot pass comment on whether the planned departure from the EU (two weeks before Valentine’s Day, no less) will lead to a flurry of births come autumn.

But we do know that Mr Johnson is wrong in saying there was a post-Olympics baby boom. In fact the exact opposite happened.

In 2012 there were 730,000 births in England and Wales, which fell to 699,000 in 2013, down 4.3%. In London specifically, the fall was almost identical - 4.4%.

This meant that the year after the Olympics, which Mr Johnson said saw a baby boom following all the expected summer 2012 amoureuse, actually saw the largest fall in the number of births in 38 years.

So how has Mr Johnson got it so wrong? Well, back in 2012 when he was Mayor of London, Mr Johnson told his statisticians to model the number of London births to test his theory.

The statisticians results predicted a sizeable increase in births. This was then proved to be not the case when the Office for National Statistics (ONS) published actual birth statistics (not models) in 2014.

As for why the birth rate dropped so significantly, various theories were proposed. The ONS suggested the precariousness of the jobs market and changes to benefits may have been factors.

Professor of Geography at Oxford Danny Dorling suggested that the change is less to do with why the number fell in 2013, but rather why it grew through the 2000s. He suggests it was a result of more women choosing to have children later in life from the 1990s onwards.

But perhaps the fall in births is a direct consequence of the British public spending a summer watching marble-carved demigods run, leap, and twirl in flattering dappled sunlight, and so finding their own partners somehow wanting. We may never know.