5:06am Wednesday. A single roll of distant thunder woke me up – it had been a sweatily hot night after several days of sultry 30-degree heat, so we were sleeping with the sash wide open.

I lay in bed waiting for the rain to start, and within seconds the first big droplets, like cluster bombs, began exploding on the plants below.

I leapt out of bed, ran to the window, pulled back the curtain and breathed in the petrichor.

“What are you doing?” asked my wife, three-quarters asleep. I was going to launch into a chemical explanation of petrichor, but at that early hour, it seemed a little cruel, and so I said: “Just researching a column.”

Then I breathed deeply on that heady, earthy, peaty, rich clean smell that comes only with the first rain after a long period of warm, dry weather – the petrichor.

I’d heard the word – pronounced petrika – for the first time only the day before, on the BBC Tees breakfast show, and now there it was, wafting wonderfully upwards as the rain came down.

It is a made-up word, but it is in the Oxford English Dictionary, and it does give a name to a phenomenon that badly needs one.

The word was created by two researchers in 1964 at the Commonwealth Scientific and Industrial Research Organisation in Australia – the organisation which invented polymer banknotes, insect repellent and wifi. “Petro” refers to rocks or stones, and “ichor” is Greek for the golden, ethereal fluid that flowed through the veins of the gods.

Essentially, petrichor is “the blood of the stone”, although the Indians have another lovely phrase for it: “earth perfume”.

The researchers, Isabel Bear and Richard Thomas, discovered that during a dry spell, plants secrete oils that stop roots growing and seeds germinating. These oils collect on the ground where they mix with chemicals produced by soil-dwelling bacteria.

As the first raindrops fall, they release the petrichor, acting as a liquid aerosol, spraying the oils into the air.

Scientists have even speculated that we are pre-programmed to like petrichor because to our agrarian ancestors, who relied on rain far more than we do, it was so important.

“Oh, that’s nice,” said my wife, and she was asleep even before the pleasant aroma of petrichor had reached the pillow.

THERESA MAY’S days are numbered, although no one knows whether that is just a single digit number or a three digit one. Perhaps the only thing going for her is that all the other candidates are fatally flawed. David Davis is the 5-2 favourite but he is such a retread that he lost in the leadership run-off to David Cameron back in 2005.

Boris Johnson is 3-1, but even the Tories have an ABB movement – “anyone but Boris”. Philip “Spreadsheet” Hammond is 7/1 but is apparently without charisma; Amber Rudd, who had a good election as Mrs May’s body-double, is 8/1 but defends a majority of only 346 in Hastings. Ruth Davidson, the impressive Scottish leader, is 10-1 but doesn’t even have a seat in the British parliament, and then on 20-1 is the treacherous Michael Gove.

So the first real contender is a 33-1 outsider, Michael Fallon, utterly unflappable and the safest pair of hands. Is the former Darlington MP worth a quid?