Andy Street of the John Lewis Partnership is not the first company boss to crack an excruciating joke, and he certainly won't be the last.

Remember Gerald Ratner, once chief executive of Ratners, Britain's biggest jewellery group? He made the mistake of telling an audience at the Institute of Directors that the only reason his company could sell a sherry decanter so cheaply was because the product was "total crap".

Ratner’s comments caused a storm, ended up on the front pages of the tabloids, and ultimately cost him his job.

No-one is suggesting Street’s job is at risk – John Lewis is Britain’s most respected and one of its most successful retailers, and the managing director is its most senior executive. But his ill-advised attempt at humour last week, at the expense of the entire French nation, has backfired spectacularly.

"Sclerotic, hopeless and downbeat" France was "finished," Street told an audience of entrepreneurs in London. "I have never been to a country more ill at ease . . . nothing works and nobody cares about it."

Street had just endured a difficult journey home from Paris on Eurostar, so was no doubt somewhat grumpy as he dubbed Gare du Nord "the squalor pit of Europe".

While in Paris, he’d picked up an award for John Lewis, which he described to his London audience as “made of plastic and frankly revolting.

“If I needed any further evidence of a country in decline, here it is. Every time I see it, I shall think of a country in decline.”

Few cheap laughs

That may have won him a few cheap laughs but Street’s comments – which John Lewis swiftly defended as “tongue in cheek” and “not meant to be taken seriously” – were unforgivable, no matter how large the grain of truth in them might be. Most of us are guilty of making indiscreet remarks from time to time. With luck, things can be smoothed over with a swift apology.

For a business, however, the consequences can be pretty serious – as Ratner discovered. John Lewis has yet to find out how serious. It is planning a French language version of its website, where online shoppers can pay in euro, and hurling insults at potential customers hardly seems the best launch strategy.

The French website is part of the 150-year-old group’s plans to double in size over the next decade. Street’s comment will make wooing French customers more difficult and could also trigger a backlash from French nationals in Britain. With up to 400,000 French citizens now reckoned to be living in Britain, largely in the capital, London is often dubbed France’s sixth-biggest city. John Lewis’s ambitions for its French website sit rather uncomfortably with the advice doled out to British entrepreneurs by Street last week, in between the “jokes” – “If you’ve got investments in French businesses, get them out quick”.

The flurry of French-bashing headlines that followed Street's reckless comments was a rare public relations slip for the group and for Street, a 30-year veteran of the business. Its department stores have negotiated the Great Recession with relative ease and its upmarket supermarkets chain, Waitrose, continues to withstand the onslaught from Aldi and Lidl.

John Lewis’s partnership structure, where employees own the business and share in its profits, is regularly lauded as the ideal business model.

It was bad luck for the John Lewis boss that France's prime minister, Manuel Valls, had several engagements in London this week, not least a high-profile meeting with David Cameron, as well as a speech in the City, an event far better attended by the press following Street's bout of French-bashing.

Street’s apology

Although accepting Street’s apology, the French prime minister gave as good as he got. Valls mused at a lunch with journalists hosted by the French embassy on Monday that perhaps the John Lewis boss “had drunk too much beer” before making his “absurd” statements. Valls added: “He announced an investment in France and then said France is finished. One has to show a bit of respect.”

The lesson for chief executives is simple – stick to running the company and leave the jokes to the comedians. They’re much better at it.

Fiona Walsh is business editor of theguardian.com