While idling in a traffic jam in Knightsbridge, I found it impossible to ignore a man standing in a queue outside the Gucci shop who broke off conversation with his friend to spit two large globules of saliva on to the pavement. Then he took a contented drag on his cigarette and continued talking just as if nothing had happened.

A few minutes later an equally fashion-conscious individual, also in his twenties or thirties, was striding along the same street. Suddenly he stopped, bent over as though punched in the stomach, and emptied the contents of one of his nostrils on to the pavement. Having completed this ablution he hoiked up a large piece of phlegm, spat it next to his initial deposit and strolled on.

Judging by appearances, neither man was a dedicated Sex Pistols fan. Both had the air of being educated and moneyed. Indeed, the irony is that the first offender probably wakes up in the morning and prides himself on being sophisticated because he buys his clothes from an expensive shop.

Conceivably, either one could have been a tourist and therefore from a country in which public spitting is acceptable. But this consideration didn’t lessen the impact of witnessing two such casual ejections of bodily fluid in so short a space of time. Having been involved in a spitting episode a week earlier, when someone unknown to me “gobbed” on my jacket in a Tube station, I found the the incidents particularly vexing.

Regrettably — especially for those who think that spitting in public is on a par with dog owners who don’t scoop the poop — it is hard to avoid the sight of sputum on our streets. Balls of the stuff seem to glisten horribly on the chewing gum-scarred paving stones of every urban thoroughfare — as would have been the case in the Middle Ages, when spitting in public was popular among all levels of society.

Close-up camera angles during games show professional footballers to be particularly prone to releasing thick droplets of saliva on to the pitch. Cricketers, too. Tennis players, with a smaller space in which to offload, are similarly adept at this insect-like exercise.

A link between some athletes’ behaviour and that of their more impressionable fans has been mooted often since the 1980s. Alan Woods, chief executive of the Keep Britain Tidy campaign, recently echoed the theory quite forcefully, though it was booted away by leading members of the football industry.

Bryan English, chief medical officer of Chelsea FC, explained that players have a physical need to spit. (It is worth noting, however, that rugby players and longdistance runners don’t seem to spit as often as footballers. Come to think of it, fans of these sports aren’t known for their propensity to spit, either.)

Nonetheless, as all pubgoing men know, it is not merely through experiencing the vicarious physical strain of others that males — for they are the main offenders — expectorate. Many of us, of all backgrounds, spit as we stand at the urinal. This tendency has always been a puzzle to me. Do men do this because they aren’t enjoying their drink? Is it a guilty pleasure, reserved just for a public loo?

“There are various forms of spitting that often carry similar levels of disgust but the meaning inherent in the different forms is not the same,” says Dr Ross Coomber, of the University of Plymouth, who has researched the sociology of spitting. “The case of spitting in urinals is probably functional more than anything else. Like a lot of spitting, I suspect that men do it out of habit after a while.

“Generally, though, there are cultural and geographical disparities to consider. In some old coalmining towns, for example, where spitting came with the job of being a miner — to try to clear the lungs — the culture of spitting remains more entrenched than in other areas.

“But these forms of spitting are distinct once again from the ‘lads’ on the street who spit aggressively on the floor or near other people. This is not about clearing the throat. Nor is it just habit. This form of spitting is imbued with meaning that is more akin to the defending of territory. We see this kind of aggressive spitting when men spit at other men.

“Wine-tasting apart, working-class cultures and sports tend to involve more spitting than do middle-class sports — and men, of course, do it much more commonly than women.

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