I’m not one of those people who believes that at a time like this clothes are unimportant. Obviously, lots of other things are immeasurably more important. But when it comes to morale, there’s a great deal to be said for pulling on a favourite dress or shirt; for taking the trouble to wear a pair of fancy earrings, even if they’ll be seen by almost no one. Not that you have to take my (vain, superficial) word for this. In 1940, the Board of Trade advised the British to keep up spirits by “preserving a neat appearance”. As shortages took hold, women began customising their drab utility dresses with embroidery and other homemade trimmings. By the time the war was over, many of them were longing as much for lipstick and nylons as they were for sugar and bacon, oranges and butter.

In some ways, then, Alexandra Shulman’s new book, Clothes… and Other Things That Matter, could not be more perfectly timed, for all that the nation’s shops, whether selling fashion or books, are currently closed. Its jacket of bubblegum pink letters on grown-up navy certainly suggested to me that it might just be the perfect lockdown pick-me-up, and among its pages, there are some lovely, resonant set pieces. Shulman understands that when we look back over our lives, lots of us find that we associate the big moments, and even the small ones, with whatever we were wearing at the time (or vice versa); she knows, too, that the buying of clothes involves complex emotions as well as, sometimes, a certain spirited ridiculousness (for her, this means a “fabulously expensive” Gucci T-shirt with a picture of Elton John’s face circa 1975 on it – an impulse buy that certainly puts my sale pyjamas to shame). If she’s good on outsize sweaters (for hiding in) and red shoes (good for showing off, even when the rest of your gear is undertaker-solemn), she’s even better on bikinis (who cares how old you are?) and holiday wardrobes (all those scrappy, floaty things you will only ever wear in Mallorca).

Like many of her industry colleagues, she likes to refer to jeans as 'the jean' and trousers as 'the trouser'

Of course, as a former editor of Vogue, a job from which she resigned in 2017, this is her natural territory; the fact that (as she’s apt to remind us) she ran that magazine successfully for 25 years is the principal reason why we want to hear from her on the subject of handbags, white shirts and little black dresses. But alas, this is also the source of her book’s flaws. Personally, I’m inclined to be indulgent of some of the more fashion-y elements of the book, mainly because they make me laugh: like many of her industry colleagues, for instance, she likes to refer to jeans as “the jean” and trousers as “the trouser”. It’s also quietly funny – side eye, as the young people say – when she describes an outfit worn by Sarah Brown, the then prime minister’s wife, as “a pleasant royal blue knitted two-piece from a mid-range label” (my italics).

But it’s a bit grim, tonally speaking, when she moves, in the space of just four short sentences, from the march to war that followed 9/11 to the growing popularity of the velour track suit (“at Vogue, we talked about how we slobbed out in them when we got home after work…”). I also wonder why, among other things, she’s so accepting of the notion that Demna and Guram Gvasalia, the brothers who founded Vetements, “had a visceral understanding of selling denim at such a premium” because jeans could only be found on the black market when they were growing up in Soviet-era Georgia (in 2019, the label was selling a pair of distressed jeans for more than £1,000). I might be wrong, but I think the root of such a “visceral understanding” may lie elsewhere.

And then there is her discretion, a quality that must have been useful when she was sitting, sphinx-like, in the editor’s chair, but which she seems now not to be able to shake off. Like Inside Vogue: My Diary of Vogue’s 100th Year, the journals she published in 2016, Clothes… and Other Things That Matter can be coy to the point of dreariness. Shulman is happy to disclose stuff about herself – for instance, that she used to suffer from panic attacks – but on the subject of other people she is as tight-lipped as if she still depended on them for patronage in the form of advertising, or fears bumping into them at some swank sponsored dinner.

When Anna Wintour or Karl Lagerfeld appear, hopes rise that she’s about to tell you what they were really like; that she will do for the fashion world of the early 21st century what the waspish diarist James Lees-Milne once did for the English country house. But, no. Wintour only looks marvellous, “a firework” in orange. Did she keep her sunglasses on during lunch at the Caprice? We never find out. As for the famously eccentric Lagerfeld, all she reveals of her visit to his Paris home is that the rooms were as big as those at Buckingham Palace (I would have gone for a full inventory of the contents of his downstairs loo at least). Maybe Shulman thinks it’s crass to dish. But I’m afraid that I’m with Diana Vreeland, the editor of American Vogue in the 60s: in life, a dash of vulgarity is an important ingredient, and it’s very much what’s missing here.

• Clothes… and Other Things That Matter by Alexandra Shulman is published by Cassell (£16.99)