In the ongoing saga of Marks & Spencer’s financial fortunes, fashion is often said to be the canary in the coalmine. The theory is that the ability of M&S to make the hearts of its core female customer sing – as it did with the pink coat (September 2013) and the suede midiskirt (May 2015) – is a crucial sign of good health for the M&S business as a whole.

The trouble with this theory is that despite consistently strong reviews from fashion critics in the three years since Belinda Earl became style director – and despite, even, the pink coat and the suede midiskirt – clothing sales have now declined for 16 out of the past 17 quarters.

So the canary parallel is starting to feel a little tenuous, or at the very least an overly simplistic way to look at a very complicated business picture. (While sales are declining, profit margins are slightly up, so the picture for investors is brighter than the headlines suggest.) And – let’s be honest – the coalmine analogy is not the most auspicious way to portray a giant of British economy and culture battling to stay relevant in the modern world.

But M&S continues to pin high hopes on fashion as a business strategy, as evidenced by the recent promotion of Queralt Ferrer, an extremely chic Spaniard who was previously head of design for the premium Autograph and Best of British labels, to overall responsibility for design.

Ferrar comes from a strong business background – in Madrid she was at Inditex, owners of Zara – but it is her sophisticated, refined, understated aesthetic that stands out in the world of high street traders.

I asked Earl why it is that her team persist with the fanfare around press days when the facts suggest that a positive response from fashion editors does not in fact translate into a booming bottom line.

“We feel we are getting the clothes right, and what we need to do now is take what happens at these press days right down the chain,” she said. “Down the chain” is M&S speak for the hundreds of minor stores that are nothing like the Marble Arch flagship at all, and is a key issue for the company.

I buy and wear a lot of Marks & Spencer clothes – today, as it happens, I am wearing a pair of oxblood patent leather ankle boots I bought last winter – but I am aware, from the surprised reactions I generally get when I explain that a complimented piece is M&S, that my success rate on the M&S shopfloor is far from universal.

“We need to buy more of the really great pieces,” says trading director Jo Jenkins. “Get the look into all the smaller stores. We’ve learnt a lot from the suede skirt. This season we’ve got a £200 leather wrap skirt, and a £200 leather skirt isn’t for everyone, but we need to translate that style in more accessible versions for all our customers.” Successes like the suede skirt, says Earl, “give us fashion authority, and that’s an asset”.

The M&S team have a habit of referring to their customer in the third person singular, as if she had just popped out of the room to put the kettle on.

“She loves a mannequin,” Karen Peacock, head of M&S Collection and Indigo, will say, asked how the customer is responding to the increased number of styled-up store dummies designed to show how the clothes work together.

“She’s getting there,” says Ferrer sagely, when quizzed on whether the M&S woman has embraced the new season’s longer skirt lengths. Also, I notice that the team hardly ever use the words ‘trend’ or ‘catwalk’ or even ‘season’. Instead, they talk about the importance of being ‘contemporary’ and of ‘key pieces’.

The philosophy behind this – a grown-up perspective on style, rather than the literal-mindedness of fast-fashion – seems sensible but it is in fact a commercial gamble, as it relies on the customer picking up on more subtle signposting.

Ferrer is gripped with fervour as she strokes the nub of an unstructured beige sleeveless suede summer jacket to show me the softness, but the average customer, with three minutes to shop for herself in between the school uniform and food departments, might not spot its appeal.

There are a few catwalk references that pop from the showroom floor. Look out for metallic pleated midi skirts (Gucci) and shoulder-frilled cotton blouses (Miu Miu); a geometric handbag (very Loewe), a black and white gingham shirtdress (hello Victoria Beckham) and embroidered bomber jackets (Versus). But the best pieces are those which have a more tangential take on fashion.

I loved the aforementioned £199 leather wrap skirt – and the £55 version, in matt silver. Also a bell-shaped jacquard skirt which looks a million dollars and costs £49.50, and a ‘cold-shoulder’ black jersey dress from Limited Collection, which channels vintage Donna Karan for £25.