If nothing else, you have to admire the chutzpah. McDonald's, the world's biggest and most controversial purveyor of hamburgers, has recently created a new job in its UK business - head of food - and filled it with a man called Mike Faers who, its PR people boast proudly, once worked as a chef at Le Gavroche, one of Britain's finest restaurants. OK, so it is quite a few years since he actually stood at the sauce station of that esteemed establishment - he ceased working for Albert Roux in 1993 - and in the interim Faers has been employed by, among other companies, McVitie's Prepared Foods (he developed the Linda McCartney range of vegetarian dishes) and Daniels Chilled Foods (he was responsible for new products at the likes of the New Covent Garden Food Company). But even so, the fact that McDonald's UK dares to bring this up at all makes one gasp - quite loudly, in my case - at its sheer audacity. First they gave us 'garden' salads and freshly ground coffee, iconic 20th-century furniture and softer lighting. Now they give us a man who knows how to bone a trotter and pack it with truffles. What next? A McDonald's cook book? An advertising campaign featuring George Monbiot and Hugh Fearnley-Whittingstall?

Would I like to meet this new 'head of food'? You bet I would. So, one sunny morning, I head to McDonald's HQ in East Finchley, where he and I, plus the inevitable corporate minder, are to hang out in the staff canteen, which is what you might call the only private members' branch of McDonald's in Britain. Yes, if you work at McDonald's HQ, you eat McDonald's - every single bloody day. 'That's why there's a little more choice here than you would get in a regular branch,' says Faers. He cycles to work from Waterloo, so he has breakfast here as well as lunch. 'Four days a week, I eat porridge [McDonald's now sells Oatso Simple Porridge in most branches]. On the fifth day, I tend to indulge myself and have a Sausage & Egg McMuffin.' And for lunch? 'It's a system of debits and credits. Four days a week, I eat a salad. One day, I don't.'

Was Faers a McDonald's customer before he got this job? 'Oh, yes. I have a long relationship with the brand. I was born in 1966. McDonald's came over here in 1974. I was at that age where it was new and exciting. I grew up through that whole process. I stopped when I started cooking for a living, but I never lost the affinity. That was one reason I joined. I've always respected the brand for its consistency. If you're in McDonald's or a three-Michelin-star restaurant, key things are the same: good food cooked by people who know what they're doing. It doesn't matter if you're doing two million customers a day, like us, or 200, like Le Gavroche. The principle is the same, and it's harder to get good, fresh food to 1,200-plus restaurants than to one restaurant in Mayfair.'

Crikey. Faers is a roundish, smiley man in chef's whites (which seem just a little over the top to me, given that most McDonald's 'chefs' wear T-shirts and baseball caps), who speaks with the practised care of one who is used to working inside big, and not always terribly popular, food corporations. He uses quite a lot of jargon - 'process' is a favourite word, and 'opportunity' - though he personally dislikes the company term for the meat that goes in your bun, which is 'patty'. 'That's one of those technical terms, but I prefer to use "meat",' he announces bravely.

His career in food began when he left school and was studying hotel management. Part of the course involved a stint working in a kitchen, and he just 'fell in love with it'. So, in the evenings, he studied for his cooking exams. His first job was at Le Manoir Aux Quat' Saisons, Raymond Blanc's restaurant in Oxfordshire, in the era when a very young Marco Pierre White was 'on the sauce' there and, after stints in a whole series of other swanky places, in 1990 he ended up at Le Gavroche. 'I spent my first year in the kitchen. Then Albert [Roux] would invite you to go to one of his global businesses. I went to Feltham, where Homerouxl [their catering company] was. The company made sous-vide [vacuum-cooked] products for hotels and restaurants. I did research and development, a natural thing for me. I'd always had a fascination with why things happen, like: why does a soufflé rise? But also fine dining is such a small niche of the food pie.' He stayed at Homerouxl until 1993. Later, he worked at Ross Young's, which made Linda McCartney products, in its factory in Hull. 'That was where I really learnt my trade - where I became value-conscious and so on.'

So, what exactly does a 'head of food' do? 'In terms of menu direction, linking that back to customers' experience, my role is bringing those together and making sure the quality standards are as they should be. Also, our consumers' needs are changing, and our menu has to reflect that. It's about choice, variety, breadth.' The likes of the Big Mac and the McChicken Sandwich, he goes on, remain at the heart of the McDonald's menu. 'They're an iconic part of our business, and so they should be. But our menu is broader than most people instinctively think. Breakfast is quite broad, from porridge to muffins to bagels. Then we move into our lunch range: our beef, chicken and fish, our salads, beverages, and sweet treats. So it's pretty broad.'

In the immediate aftermath of the publication of Fast Food Nation, Eric Schlosser's brilliant and masterful 1991 demolition job on McDonald's and businesses like it, the company saw a marked fall in its profits, and branches began to close. But the company fought back. Not only did its spin doctors go into overdrive, establishing the website Make Up Your Own Mind, where customers could have their questions answered - even questions like: 'Every time I eat a McDonald's, I have an urge to go to the toilet. Do you use laxatives in your food?' - with apparent transparency. It began selling salads, and reduced levels of salt and sugar in its products. Now, the focus is to be on 'premium'. Coming to a branch near you soon: the M, a more... upmarket burger. But don't get too excited. We're hardly talking grass-fed Aberdeen Angus, served rare with a dash of Dijon.

'If you think about the Big Mac, a lot of the flavour is delivered through the sauce. There's quite a lot going on there with the pickles. The M has a different philosophy. The bread is ciabatta, stone-baked. It's as good as anything you can buy in Marks & Spencer. But the beef is the hero of this product. We've gone for coarser mince, and select cuts: we've gone to the forequarter, and we've taken select muscles off the animal, and minced those. It will have a more... textured mouth feel. Then some batavia lettuce, a slice of tomato and a tiny bit of salad dressing. It's a case of less is more.'

Do customers worry about the kind of life the cow they are eating has led? 'To be honest, that's not my area of expertise. But you'd be surprised at the standards we expect: how rigid they are.' Hmm. At this point, the minder reminds me that McDonald's eggs have been free range for a decade. And its chicken? 'It is, er, broiler. So it's big sheds, but it's not caged. Welfare is important.' And the good news is that the Chicken Selects range and the Chicken Legend contain - wait for it - whole pieces of breast. The company has grown adept at this sort of thing: at making stuff that should be standard - whole bits of meat! - sound revolutionary. It's a crazy kind of sophistry. Just as when, later, Faers tells me that what customers really love is a 'nice bit of batavia lettuce'. I'm not sure that most people can tell batavia from romaine; they just want it to be crisp and fresh. But batavia happens to be a cultivar with an unusually long shelf life. QED.

Before I leave McDonald's HQ - the remains of my cappuccino, made from freshly ground Rainforest Alliance-certified beans, are now tepid - I ask Faer if he regards his new job as a responsibility. I'm not talking about his effect on company profits. The fact is that McDonald's serves millions of people every day, some with extremely limited financial resources. Whether he likes it or not, he is now a player in the ongoing debate over our growing levels of obesity. For the first time in nearly an hour, I feel the atmosphere cool. 'Yeah, yeah,' he says. 'I understand what you're saying. But it's not my greatest area of expertise. I have two young kids. We use McDonald's. But we use it infrequently, not every day. It's a treat. They have McNuggets and a bag of fruit. It's about personal choice.' I find myself longing to agree with him; he's only trying to earn a living, after all. But we must cling to facts. A McDonald's 'Fruit Bag', containing sliced apple and a few grapes, counts as one of the five portions of fruit and vegetables that the government recommends we eat daily; the best I can say of Chicken McNuggets, which contain some 20 ingredients, is that they're cooked using a non-hydrogenated vegetable oil. Besides, the last thing that McDonald's wants is for people to use it only for the occasional treat. This is why it has put so much energy into selling coffee and 'deli sandwiches' to office workers. This is why its 'pound saver menu' still features eight items, including a bacon cheeseburger, that can be yours for a mere 99p.

Back on home turf, I visit McDonald's for lunch. The last time I ate in the fast-food chain was in 2001, when I interviewed Atomic Kitten. Those girls were mad for Cadbury's Creme Egg McFlurries (a McFlurry is an ice-cream concoction that changes flavour with dizzying frequency; the current limited edition is the Oreo McFlurry, containing bits of the favourite American cookie that is eager to establish itself on these shores) - and they insisted I try one. It was... well, sweet. So it's really only fair that I call in.

My local branch has been converted, along with thousands of others, from a plastic hell of red and yellow to a superficially stylish homage to Arne Jacobsen: a rolling programme of transformation that is paying good dividends for McDonald's (refurbished restaurants see an average uplift in sales of six per cent). But the menu still seems pretty limited to me (menus do vary from branch to branch). The only salad that seems to be available today - and, even on a full menu, I believe there are only five; the term 'Salads Plus' is a complete misnomer - is a garden side salad, and the deli sandwiches look to me to be just as calorific as certain burgers (later, I find that this is indeed so; according to the McDonald's website, a toasted deli chicken salad sandwich with no cheese on a brown roll contains 365 kcals; a cheeseburger contains 300). Oh, what the hell. In the end, I have orange juice, a side salad and a limited edition (on sale for one week only) New York Supreme: a burger, bacon, cheese, tomato, creamy mayo and - you guessed it - batavia lettuce in a watersplit sesame-topped bun. It comes with fries. The whole lot costs me £5.78, and a whopping 997 kcals (an active woman of 45 needs about 2,000 a day). The juice and salad are fine. The chips are unsatisfying. The bun is sweet. The bacon tastes artificially smoky. As for the beef, it's a grey circle that, eaten alone, is like no meat that you've ever tasted before, and I don't finish it. I will say this, though: the girl who served me was lovely.

Has McDonald's changed? Not really. Most of what it has done in the last five years is either tinkering, window dressing, or spin. Of course I'm glad that - to take one example - it has cut the salt in chicken patties by 20 per cent. But in the scheme of things, such shifts are small fry. A Big Mac still contains a quarter of the calories a woman requires daily, and a third of the salt. So, last year, the company sold two million salads. But divide that by the number of customers it serves annually, and that works out at only one salad per customer per year. Hardly a revolution. I despise, too, its weasel words. The company talks of 'sourcing local produce' when what it means is buying British beef; frozen meat that travels from, let us say, South Shields to Southsea is hardly 'local'. I commend the Make Up Your Own Mind website only because its 'transparency' is so robotically hilarious. (Sample question: 'Why are your burgers just pieces of tasteless rubber?' Sample answer: 'McDonald's does not believe that its burgers are tasteless.') And all this before we even get to global issues such as the way slaughterhouse workers in the US are treated, or the manner in which it is currently pushing its way into China. In this context, semi-boasting of a head of food who once worked at Le Gavroche is verging on the insulting. Just how dumb does McDonald's think we are?

But you don't only have to take my word for it. Eric Schlosser, who has often himself been on the - how shall I put this? - sharp end of McDonald's spin, believes that, though the company has made some important changes in its day-to-day operations, we should not let that distract us from the ethos that lies at its heart. 'In response to criticism, McDonald's has done some good things,' he says. 'They've eliminated trans fats in the United States, added organic milk in the UK, raised the wages of Florida tomato-pickers, and made it possible for kids to get carrot sticks instead of french fries with their Happy Meals. All of that genuinely deserves praise. But the fact remains that McDonald's still earns the bulk of its profits aggressively marketing hamburgers, chips and sodas to poor people. Never underestimate the power of multimillion-dollar advertising budgets. How long will this continue? For as long as we let it.'

Room for more fast food?

On our food blog, Rebecca Seal tried Burger King's £95 burger