Going up or down?

The skyscraper

What it says: “I have amazing legs. Oh, and I am much younger than you.”

As worn by: Daisy Lowe, Agyness Deyn, all models, girls in Topshop hoping to be model-scouted, Pixie and Peaches Geldof, the cast of Gossip Girl, Alexa Chung. Photograph: Yui Mok/AP

How to wear it: Daisy Lowe rocks this look best: opaque tights, heavy fringe, deadpan stare and legs that look Photoshopped but aren’t. Alexa Chung does the same length skirt, but with a tomboy-at-St-Trinians thing going on: leather satchel-type bag, blazer with the sleeves rolled up, over the knee socks, slightly clompy shoes. Photograph: David Levene/Guardian

Don’t: Spoil the effect with leg-flattering poses à la Liz Hurley and Victoria Beckham: go for a knock-kneed ingénue model stance, or one knee turned out à la Agyness Deyn in a Burberry ad. To be really, really annoying, wear with flat shoes and thighs that still don’t meet in the middle. Grrr. Photograph: Kristie Bull/AP

Old-school miniskirt

What it says: “I may not be as young as I used to be, but I still have amazing legs.”

As worn by: Kate Moss, Carine Roitfeld, Chloe Sevigny, Jade Jagger, Cameron Diaz, Tamara Mellon. Photograph: Astrid Stawiarz/Getty

How to wear it: For the sexpot whose Lolita years are behind her, the hemline heads south a few inches. Perhaps the upper thighs are not what they were post-30 or post-babies; perhaps there is simply a limit on how many times one feels the urge to flash gusset at the paparazzi. Photograph: PA

Once upon a time, the older-but-still-foxy chick moved gracefully into jeans at this point, but Jennifer Aniston’s current media profile as permanently denim-clad Ex-Babe Unable To Keep A Man has given jeans a bad name. The classic-length mini skirt is still racy enough to declare one’s commitment to remaining in the public eye, but not so short as to invite ridicule (and unfavourable comparison with Daisy Lowe.) Photograph: Richard Young/Rex Features

Just-above-the-knee

What it says: “I have class — oh, and good genes.”

As worn by: Kate Middleton, Chelsy Davy, skirt-suit-wearing office crumpet everywhere. Photograph: Dave M. Benett/Getty

How to wear it: Traditionally, a finely sculpted knee suggests high breeding, which goes some way to explaining why those of us of thick peasant stock will never rid ourselves of the kind of sturdy knees which are great for scrubbing floors but no use whatsoever when trying to look good in shorts. Photograph: Getty

Kate Middleton’s racehorse legs are her secret weapon in the quest to be Queen — or not so secret, now that she’s passed the trick on to prospective sister-in-law Chelsy Davy. Having fabulous legs yet keeping your thighs under wraps shows self-restraint and decorum, which goes down a treat with stuffy in-laws. Photograph: David Hartley /guardian.co.uk

On the knee

What it says: “Young at heart.”

As worn by: Sarah Jessica Parker, Kelly Brook, Lily Allen, Louise Redknapp, Anna Wintour. Photograph: Claire Greenway/Getty

How to wear it: A full skirt to the knee is the style most often worn by women who think of themselves as girls. A skirt that ends bang on the knee shows off the curves of the calf and ankle whilst drawing a discreet veil over the thigh. It looks wholesomely Boden-esque and wifely with a kitten heel, or kookily Carrie-ish with a platform or stiletto. Photograph: Dave M. Benett/Getty

This is also the favoured length of women who wish to avoid undignified squished-thigh syndrome when they sit down in public: when attending fashion shows, Anna Wintour rarely strays from her established formula of a full-skirted, Prada-style dress to the knee and a pair of subtle, low-heeled Manolo sandals. Photograph: Harry DiOrio/Getty

Calf-length

What it says: “I’m On-Trend, and that’s what counts.”

As worn by: Gwyneth Paltrow, Christina Ricci, Penelope Cruz, Victoria Beckham. Photograph: Doug Peters/Empics

How to wear it: Wearing calf-length is this season’s way of telling the world you read Vogue. It is so very fashionable that you won’t even see it in the shops yet, because this is next season’s trend. The trouble with fashion, of course, is that it is so very often at cross-purposes with old-fashioned notions like Looking Nice. (You will notice that Anna Wintour, though presumably well aware that calf-length is quite the dernier cri, does not go near it with a bargepole.) Photograph: Pascal Le Segretain/Getty

Gwyneth Paltrow, who is currently on a mission to prove to the world that she is in fact a hot fashionplate rather than just half of London’s premier pair of macrobiotic miseryguts, is into calf-length right now. Victoria Beckham, who would wear a terrycloth nappy in public if it had a designer label and she thought it would make her more famous, is also working the look. Photograph: guardian.co.uk

Floorlength

What it says: “I have glamour, but I also have gravitas.”

As worn by: Angelina Jolie, Dita Von Teese, Cate Blanchett, everyone at the Oscars. Photograph: Doug Peters/Empics

How to wear it: The floorlength gown has enjoyed a phenomenal revival over the past five years. Not long ago, floorlength hems were restricted to brides and the stuffiest of White Tie invites, but now even hip young Hollywood gunslingers can’t get enough of this look — and in the form of the maxi dress, it has entered civilian wardrobes too. Photograph: Doug Peters/guardian.co.uk

The word “gown” has reentered fashion parlance to refer to “wearing long”. Actresses who are trying to escape being defined by their world-class beauty — I know, doesn’t your heart just bleed for them, huh? — know that by refraining from showing your legs, you get to look like a serious artist. What’s more, floorlength is a red-carpet trump card: wear it, and anyone in a shorter dress looks like your assistant. Photograph: Doug Peters/guardian.co.uk

Floorlength plus

What it says: “Tonight is about Me. ME!”

As worn by: Kristin Scott Thomas, Goldie Hawn, Monica Bellucci. Photograph: Paul Smith/Empics

How to wear it: What to wear to steal the show when everyone else is wearing floorlength? Floorlength with a train. The more like a wedding dress it looks the better, frankly, because this will subliminally influence people to look at you and only at you. You can guarantee that you will be given a regal amount of personal space, because your outfit will be taking up most of the room. Photograph: Hahn-Nebinger-Orban/Empics

What’s not to love? Cast your mind back to the 1981 Royal Wedding, and Princess Diana’s 25-foot train: if that’s not a template for stealing the show at the Oscars next year, I don’t know what is. Photograph: Doug Peters/guardian.co.uk