McDonald's has announced the creation of 2,500 new British jobs. Over the last five years, in fact, the company increased its UK workforce by 20,000 – a rise of over 20%. Many of these McJobbers will be workers on benefits or "Wobs", of course, and they'll still be miserably underpaid on seven or eight quid an hour while, last year, the company's chief executive James Skinner took home almost $9m.

But whatever its reputation among those of us who care about working conditions, public health, the environment and the quality of the food we eat, McDonald's is still doing extraordinarily well. Every day, 68 million people visit one of its restaurants. If you'd bought its stock in 2004, when Morgan Spurlock released Supersize Me and some people predicted the eventual death of the giant, you'd have tripled your money by now.

The McDonald's PR campaign of the mid-noughties has undeniably been a success. But did the chain actually improve, or were its changes merely cosmetic? In the UK, at least, I would argue McDonald's felt genuinely compelled to act on some of the concerns people had raised about it. It introduced more salads and fresh fruit to its menus, it began to use only free-range eggs and organic milk, it made its revolting coffee Rainforest Alliance and it began to recycle much more than it had before. People argued, with some reason, that the lettuce leaves were just fig leaves: that healthy-ish food in a burger joint was only a "vehicle to sell more burgers and fries", as one anti-junk food campaigner put it to the New York Times.

In part, she was probably right. But Jamie Oliver was right as well: it's now possible to eat a relatively healthy meal in McDonald's. (This is if you define "healthy" as merely "not high in fat and sugar": a narrow definition, but the most important in the debate on obesity.) This is an undeniable improvement on the situation 10 years ago. Many people thought that putting calorie counts on menus would look stupid or nannying, but those numbers turned out to make it much easier for people to make better choices about the food they buy. Middle class as I am, I use them in Pret sometimes. Anyone could guess that a ham and cheese toastie is going to be more calorific than a tuna salad, but few would necessarily have realised the toastie has well over three times as many calories as the tuna.

While it's clear that McDonald's continues to make it easy to eat very badly for very little money, I'm not convinced it's reasonable to blame it alone for the obesity crisis. Blind though it perhaps is of me, I still marvel that it can raise, kill and butcher a cow, make a bun and cheese with all those weird chemicals, lurid colours and sugar, van everything round the country or the planet, pay the rents on the restaurants, hand its staff their abysmal wages or million-dollar bonuses, market itself ferociously, and still sell a cheeseburger for 99p.

I'm no convert to McDonald's. Its pay remains a disgrace; its core product deeply unhealthy (a "Big Tasty with Bacon", large fries and medium chocolate milkshake has 1,780 calories) and it retains a pathological hostility to trade unions. I was as revolted as anyone at its presence in those monolithically ugly premises in the Olympic park. But under pressure from campaigners it has been forced to improve a little in the last few years. The correct response is not applause, it should be to intensify that pressure.

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