It is​ a fascinating and fawning exhibition. At the King’s Gallery (until 18 October) some three hundred items of clothing belonging to Queen Elizabeth II are displayed – headless, limbless, fleshless – like the remains of extinct animals. Norman Hartnell supplies silky flamboyance and encrustations: lace re-embroidered with sequins and crystals. Hardy Amies, fresh from a ‘distinguished career as a spy’, offers a see-through mac and trim day dress praised for being figure-flattering but ‘demure’. There are Horrockses horrors designed to make anyone of five foot four look like a parcel as well as a Wedgwood-inspired outfit from Angela Kelly which turns the monarch into a tea set.

Pictures of the ceremonial robes – the royal family stand in puddles of ermine as if they have leaked – provoke the least comment from viewers in the jammed queues. The crinolines are the most ogled. Hartnell was urged by George VI to find inspiration in the court portraits of Franz Xaver Winterhalter. ‘I bet she was pleased when she saw that,’ the woman in front of me said. There are items of insinuating familiarity: ‘I’ve got a picture of Granny with a hat like that.’

Questions are answered. What could ‘fancy dress’ mean for a princess? Not, it turns out, clogs and shawls, but Tudor-style damask and ‘a golden fairy dress and knickers, wings and wand’. There are three main surprises. A fringed suede jacket worn over an evening dress. A pair of culottes in purple chiffon, described as ‘a rare but interesting departure’. And a ‘poodle skirt’, which came out for a 1951 square dance in Ottawa. The dog-disloyalty (corgi socks are for sale in the gift shop) is more implied than actual. The flared skirt was named after the shape most often appliquéd onto it; the felt decorations on the queen’s skirt are of a bendy-legged Romeo with Juliet poking out of her balcony like a pot plant.

Seen in close-up – and clear close-ups are one of the achievements of Caroline de Guitaut’s exhibition and accompanying catalogue, Queen Elizabeth II: Fashion and Style (Royal Trust Collections, £40) – the coronation gown is less a garment than a breakaway chapel of Westminster Abbey dedicated to horticultural abundance. The queen insisted that the dress, embroidered with bugle beads, crystals and ten thousand pearls, should feature not only the emblems of the British Isles but also those of the Dominions. Alongside wattle, silver fern and maple leaf are lotus, wheat, cotton, jute and protea. Hartnell, who had been alarmed to discover that the national emblem of Wales was not a daffodil but a leek, made the vegetable ‘a vision of Cinderella charm’ by sprinkling ‘the dew of diamonds’ on silk. Like a mason working on a medieval cathedral (not a comparison he would have relished), he left his own mark in the shape of an extra uncommissioned four-leaved shamrock on the left side of the skirt.

Guitaut’s book includes some striking palace spreads: evening dresses by Hartnell and Amies (sherbet pink with sleeves and a bow at the waist, lemon yellow with side bows) standing in front of gilt and chandeliers; three creamy Hartnell gowns on a crimson carpet. Untenanted frocks in a glass case are specimens; pictured among furnishings, they become fabric phantoms and look incomplete. The shoulder straps stand up from the bodice like handles.

All the gowns save the stiffest would benefit from being seen on a human frame. In motion, the dark blue velvet and purple satin of a 1958 number must swish and merge; the heavily embellished coral-reef surface of a pea-green piece might at least glint. Movement exposes an apparent decoration as a feat of engineering. A satin evening dress – designed in Pakistan’s national colours for a banquet given by President Ayub Khan – has a waterfall pleat at the back which, when still, seems merely a flourish. A sketch by Hartnell shows it in action, with the body inside leaning slightly forward. Fully unfurled in emerald green, against the white skirt, that pleat looks like a propeller. It is surely time for galleries and museums to find ways of showing material on the ripple; if they can’t have models stalking through coffee shops as they did in 1950s department stores, then put copies on a catwalk to the sound of Duke Ellington’s Queen’s Suite.

Awe breeds inertness. No one would expect an exhibition at the King’s Gallery to offer an incendiary commentary, but the usefully fact-packed catalogue is blotted by supine courtiership. Dame Anna Wintour’s breathless preface finds that ‘fashion people’ cleave to the queen: ‘the constant, the forever, the absolute confidence of staying true to oneself’. Amies ‘appreciated seeing my queen in one of my dresses in her own house’. Reverence is folded into otherwise helpful paragraphs. Her trendsetting headscarves get a curtseying adverb: they are ‘knotted neatly’.

The most intimate items are the most casual. Chestnut-brown shoe trees stick up from a pair of brogues that gleam like well-brushed dogs. A navy blue attaché case, which looks as if it were made for explosives, is packed with monographed brushes and jars ready for face action. Some French dolls come with tiny Citroëns; those by Lanvin wear gold laurel-leaved headbands, echoing the belts on the English princesses’ dresses. In 1930 the future queen’s doll Pamela was dressed by Smith & Co in a cherry-red woollen coat trimmed with rabbit fur. Despite her cherub cheeks, Pamela looks canny, less jolly than her owner, as if she knew what was in store.