TO HEAD a retail group, it is commonly supposed, you need a dash of flash, an eye for detail, a nose for trends, a bit of bluster and a charismatic appeal to shoppers, staff and suppliers alike.

To head a retailer, in other words, it helps right now to be Philip Green (self-made billionaire, acquisitive boss of BHS and Arcadia, and current UK “retail wizard”). So what price Roger Holmes? “It is true,” says Holmes, the quietly spoken boss of Marks & Spencer, “that I am not Philip Green.” He gives a rueful smile. “But if you look at successful retail businesses, you’ll see there are some quite different characters leading them.”

But few, I would guess, as low-key and thoughtful as Holmes. Still only 43, trim, brown-eyed, good-looking, grey just beginning to fleck his thick black hair, he is already into his second year as chief executive of Britain’s highest-profile chain store and is beginning to feel the heat.

Last week M&S announced interim figures that came up to expectations — pre-exceptional profits climbing to £311m, total group sales rising 3% — but they were still not good enough for some analysts and commentators. M&S’s share price subsequently slid. Holmes’s honeymoon is definitely over.

What’s the problem? Behind the profit figures, three consecutive quarters of flat clothing sales are not impressing anyone. The questions are now coming thick and fast. Why are sales not rising more quickly? Where is the growth going to come from? M&S went into the red at the end of the 1990s and then rebounded, dragged back to financial health by Holmes and his chairman Luc Vandevelde, but were the early signs of recovery just a false dawn? Worse than that, it is beginning to get personal. The press is beginning to pick up the first whispers of unhappy underlings (Holmes takes too long to make decisions) and unimpressed former executives (never a shortage of those at M&S). A clear agenda is being mapped out: Holmes, nice man, engineer by training who has moved through consultancy to line management, first at Kingfisher, more recently at M&S, is just too downbeat, too process-driven, for a retail sector that is getting quicker and more instinctive by the minute. Where is the flair? Sitting at the glass meeting table in his first-floor office in M&S’s London base, surrounded by the firm’s products — clothes on a rack, advertisements on the wall, price tags on his leather sofas — Holmes shrugs when I run it all past him. His line is simple: we know we can do better, we are working on it. Just get it in perspective.

“When I came in, this company was a business that had lost confidence in itself and lost a sense of why it existed,” he says. The shops were getting shabby, other retailers were stealing its market share. That’s all been turned round.

“We can tell from how customers feel about us that we are in a different place from two years ago,” he says. He has brought in retail superstars like George Davies, founder of Next, and Vittorio Radice, former boss of Selfridges, to provide oomph. He has strategies in place for the four key areas: cheaper suppliers for key clothing ranges; a new chain of food-only stores being rolled out; a new credit and loyalty card; and the first stand-alone homewares store, masterminded by Radice, opening next spring. Now it’s just about getting the little things sorted and waiting for the improvements to boost growth.

As for comparisons with Green’s success at BHS, well, hang on, says Holmes. Green is not boosting sales at BHS, just running the place much more profitably. Do he and Green ever compare notes? (The words “chalk and cheese” spring to mind.) Holmes gives a little smile. “I saw him at a function the other night. We don’t talk that much.”

If the pressure is telling, Holmes doesn’t show it, that’s not his style. Outwardly, he is modest, self-deprecating, tentatively charming; underneath steely, driven, phenomenally hard-working. As anyone who has met him will tell you, he is a very impressive act one-on-one. He can give you the 10-year version of “what went wrong at M&S”, or the 18-month overview — all in intricate detail, backed by research.

In that, he is a technocrat, hand-made by McKinsey, the consultancy where he worked before Kingfisher and which also produced Archie Norman, who turned round Asda before going into politics.

“Roger is very calm, very unflappable, very good at his job but very inscrutable,” says one friend. You might get a little grin, but the bushy eyebrows rarely frown, the eyes are unreadable. Nobody doubts his ambition — this is the man who seriously angered his former boss Sir Geoff Mulcahy by walking out of Kingfisher to head M&S’s UK stores. His colleagues just wish a bit more was visible on the surface.

Is that relevant? Probably not, but that’s what you get when you run a business as close to everyone’s heart as M&S. “Yup, I’m used to everyone having a view,” says Holmes cheerfully.

He tours the stores on Fridays and always politely sits and listens to what anyone has to say, bigger knickers, smaller knickers, where’s the cashmere, the hipster hosiery, my favourite stir-fry? It must, if you think about it, drive you slightly crazy as a boss.