IT’S a truly disgusting image. The ultimate in unacceptable behaviour. A male driver winds down his car window and spits a full mouthful of grey phlegm into the face of a female passenger in the car alongside.

It was a cartoon in yesterday’s Times. The female passenger was Theresa May and the male driver unleashing the shameful shower was Vladimir Putin.

But, of course, the cartoon was based on a real life event: former Liverpool footballer turned TV pundit Jamie Carragher spitting from his car at a driver who had been needling him, hitting his 14-year-old daughter in the passenger seat. Carragher, who summoned up a remarkable volume of spittle for very little effort, has been suspended by Sky for the rest of the season as spitting is one of the last great taboos.

In the mid-1990s, I had an interview with Tony Blair at his house in Trimdon Colliery, which was impossible to find in the unnavigable maze of the Trimdons. I set off early, located the house and had time to kill in a nearby pub, which was a spit and sawdust sort of place. I sat there, nursing my orange juice, amazed as a succession of men got up, walked across the lounge, expectorated into the fire with a loud hiss, and then returned to their seats as if this were the most normal behaviour in the world.

Indeed, it once was. In medieval times, apparently, people thought it impolite to swallow saliva and so they commonly spat it out. Spitting was increased by the growing popularity of chewing tobacco, and dirty industry added to it: if you’d spent 14 hours amid the black dust of the coalface at Trimdon Grange Colliery, you’d want to hockle up and clear your airways in the pub.

In some cultures – Indian and eastern Europe – spitting was encouraged as a way of warding off the evil eye. It was thought that if you idolised someone it would cause the evil eye to curse them, so in some societies you spat at a person after you had paid them a compliment to show the eye you didn’t think they were perfect.

European attitudes began to change in 1882 when Robert Koch identified the TB bacterium and people realised that spitting could spread this feared disease. The 1918 flu pandemic heightened concerns.

Spittoons, with sawdust on the floor to soak up wayward shots or even spitsheets behind if people’s aims were consistently terrible, encouraged people not to spit on the floor. Spittoons were usually made of brass and had an antiseptic solution in them – the US Senate chamber retains a pair of very attractive late 19th Century brass spittoons as a decorative reminder of the flobbing days.

China was the last bastion of public spitting, not outlawing it until the Sars crisis of 2008. It used to be so common that in photographs of the 1972 meeting in Beijing between Chairman Mao Tse-tung and US President Richard Nixon, you can clearly see that two, white porcelain spittoons have been strategically placed beside their chairs in case either world leader felt compelled to do a Carragher.

Now the only place where spitting is acceptable is the football field – rugby and cricket players don’t seem to expectorate so much, presumably because of the different class origins of the games. Vladimir Putin is too much of a gentleman to gob in public, although he seems content to allow his henchmen to unleash toxic torrents of nerve gas on British street corners.