BEFORE circumstance left me standing on this ledge, I was often astride my bicycle. Man and bike are still to be found in perfect harmony, although not every day.

Cycling is the best and worst way to get around a city.

Best because it’s free, easy and good exercise.

Worst because of heavy traffic, HGVs the size of houses, buses that hop through red lights, electric buses that sneak up on you, cars coming so close their wing-mirrors give you a free back massage, U-turning taxis, car doors flung open without warning, holes in the road, broken glass strewn along streets favoured by hen parties and booze-cruising louts, and crazy fellow cyclists ­– not to forget pedestrians making kamikaze dashes across the road, headphones plugging their ears and eyes seemingly put on inside out by mistake that morning.

So I know why Boris swore.

According to reports yesterday and this morning, the Mayor of London and newly elected MP for Upper Blustershire (or somewhere) got into an argument with a black cab driver. The exchange of un-pleasantries ended with Boris offering that good old Cockney greeting: ‘Why don’t you f*** off and die, who don’t you f*** off and die – and not in that order.”

To which the cabbie responded with the traditional Cockney retort: ‘Yeah bollocks, I hope you die.’

Ah, let me take you to the streets of London…

The reported exchange was sparked off by the continuing row in the capital as Uber drivers undermine the traditional taxi trade by undercutting fares and allegedly not paying taxes, and also using sat-navs instead of having to learn the knowledge. They are presumably also not aware of important local customs, such as the swearing in the street of the mayor.

So what are we to make of this colourful stutter in the long march of Boris Johnson’s ambition to lead the Conservative Party? Brand Boris won’t be hurt by this contretemps as he seems to survive any potentially embarrassing situation with his jolly twit persona intact.

Yet Boris the nation’s upper-class fool is, Man On Ledge suggests, only a tiny part of this most ambitious man’s complex character. The exchange won’t have done him much if any harm, but if he’d like to find some different motorists to swear at, he could always bring his bicycle to York.

Incidentally, I did enjoy the quote in one newspaper, in which ‘a source closer to the mayor’ said: ‘Boris has dozens of chance conversations with Londoners every week. Many are productive and friendly, some are colourful, I know most end happily. I believe this particular cabbie however is a serial heckler.’

As too is Boris himself, the national’s serial heckler ­ – but not a cereal heckler. That would be a man who shouted at cornflakes.