Secrets of the Museum

Inside every museum is a hidden world, and now cameras have been allowed back behind the scenes at the world-famous Victoria and Albert Museum in London. Although many of us have had to stay away over the last year, the work has continued in the V&A's workshops and storerooms to conserve some of the two million wonders in the museum's collection.

In this episode, the museum sonservators work to preserve and maintain four unique objects. Theatre and Performance keeper Geoff and conservator Jo work to repair an eye-popping red lurex suit that belongs to Jim Lea, the bass player in one of biggest glam rock bands of the 1970s, Slade. Meanwhile, curator Peta and conservator Victoria are finally able to bring a 500-year-old wax modelled by Michelangelo out of cold storage, but it isn't long before they find something on one of the buttocks that takes them both by surprise.

Curator Elania, while working on a display showing the prominence of watercolour painting during the Renaissance, disovers a series of unusual white dots on a piece by a Flemish master that hasn't been shown for over a century – Christ, St Paul and the Theological Virtues, by Jacob Jordaens. And finally, curator Josephine and keeper Anna aim to prepare a kimono, designed by the Cameroon-born designer Serge Mouangue, in order to add it to a touring exhibition celebrating the Japanese national dress.

As the V&A's Museum of Childhood in east London prepares to undergo a major refurbishment, its collection of over 30,000 toys and games must be packed away - including the museum's oldest teddy bear, the 111-year-old Little Tommy Tittlemouse. Curator Will must ensure its good condition before it can be put into storage.

With the V&A preparing for a new exhibition on the art of Iran, curator Tim hopes to display some of the longest artworks ever unveiled at the museum: three ten-metre-long replicas of the painted interiors of mosque domes from central Iran, dating from the 1850s and created by local Iranian craftsmen. After more than a century in storage, these vast objects need extensive conservation, but conservator Nicola has only 16 weeks before the they are installed.

In the Jewellery Gallery, curator Clare has two new pieces she is hoping to add to the collection. The first is known as the Vulcan ring, made by contemporary British designer Emefa Cole as part of a series inspired by the power and majesty of volcanoes, while the second is the Peony Brooch by Taiwanese designer Cindy Chao, fashioned from 105 large oval rubies held in purple titanium.

In the British Galleries, curator Simon has found the perfect object for the Laughing Matters display, which celebrates the history of Britain through comedy: the costume worn by Andrew Sachs in Fawlty Towers. The outfit is being donated to the museum by Sachs's daughter Kate, who recalls memories of visiting her father on set and reflects on how her father's own immigrant background escaping from Nazi Germany in 1938 would have informed his portrayal of Barcelonian waiter Manuel.

Curator Kate from the Theatre and Performance Department embarks on one of the museum's most ambitious exhibitions to date. Celebrating Lewis Carroll's Alice in Wonderland, Kate wants to take visitors on a trip down the rabbit hole and into the imaginative world of Alice. At the heart of the exhibition, Kate hopes to recreate the famous Mad Hatter's tea party, as seen in the famous 1966 film. To help pull off her bold plans, Kate has enlisted world-renowned theatre designer Tom Piper – but turning a scene from a film into an immersive installation proves more difficult than they had bargained for.

Meanwhile, for print curator Gill, it's a dream come true when they acquire a rare set of prints from Lucian Freud. In order to discover more about them, Gill meets Freud's former assistant David Dawson, who explains how Freud created his etchings and worked with his printer, and Freud's daughter Bella, who shares rare personal insights into how her father worked.

The V&A's fashion curator Oriole is always on the lookout for fabulous pieces to add to the museum's collection. This time, she manages to acquire not one but two standout pieces: one of the signature dresses by famed designer Molly Goddard and a men's colour-block cardigan designed by JW Anderson, which sparked an unlikely worldwide crocheting craze on social media after the influential pop star Harry Styles was seen wearing it.

Over in the Textile Gallery, roof repairs mean that one of the museum's greatest treasures must be moved. The Devonshire Hunting Tapestries are almost 600 years old and masterworks of the weaver's art. Their enormous size means they are hardly ever moved, but now conservator Frances needs to take them off the wall safely. But before they can be taken down, she has to check every inch to make sure they are stable enough to travel on loan back to their former home, Chatsworth House.

Conservator Susan is at the centre of an epic conservation project that will take 20 years to complete: conserving a unique set of Chinese paintings called The Ten Kings of Purgatory. These rare works have been in the V&A's stores for 150 years, but before they can go on display for the first time, each King of Purgatory must undergo extensive conservation. Susan has already worked on two of the kings, having learnt from a master craftsman at Nanjing Museum how to conserve them using traditional Chinese techniques.

Now she is deploying her new-found skills in conserving king number eight, which will involve dousing the watercolour and ink paintings with very hot water and applying new lining paper made with yasha, a traditional Japanese dye created from cones of the alder tree. It is not a process for the faint-hearted, and as Susan manoeuvres almost two metres of soggy painting on to a special upright board to dry, there is a chance that the delicate paper may tear.

Meanwhile, the Theatre and Performance department has just acquired one of the favourite outfits of legendary pop diva Dame Shirley Bassey. Curator Simon is keen to get the spectacular skin-tight catsuit on display, but the costume, encrusted with sequins, crystals and beads, needs some serious conservation first. Made in 1969 by British couturier Douglas Darnell, the body-hugging sheer silk chiffon outfit was worn by Shirley Bassey on and off for 30 years; first on the album cover of her famous Bond title song Diamonds are Forever, then through a number of stage performances, culminating in her 60th birthday concert. Getting it ready for display will take hours of careful stitching, with specially adapted needles and sheer threads kept in perfect tension, to ensure it is ready for its new starring role.

Finally, the glittering catsuit is dressed on a specially made fibreglass Bassey mannequin. Here it can be reunited with a gold lame cape trimmed with turquoise-blue ostrich feathers, made to accompany the outfit, before its debut in the gallery.

Over in the cafe area, a major refit provides an opportunity for a flamboyant Victorian majolica vase, dedicated to the god of wine Bacchus, to shine for the first time. The colourful vase, decorated with goat-like satyrs sticking their tongues out, was made in 1883 by the innovative Minton factory in Staffordshire. Minton also decorated the museum's Gamble Room, part of the world's first-ever museum cafe.

Minton became one of the most important ceramics manufacturers of the Victorian era after developing a new technology that could produce majolica, a type of colourful ceramic, by firing many-coloured glazes all at once at low temperatures. When Queen Victoria ordered some of Minton's majolica for Buckingham Palace, the colourful objects became the must-have decor of the Victorian era. But the Minton vase must undergo a deep clean before it is ready to take its place in the newly refurbished cafe.

The museum collects objects both old and new. Over in the sculpture department a new acquisition by contemporary sculptor Eleanor Lakelin, Echoes of Amphora, is joining the collection. Eleanor's unusual sculpture looks like it is made from clay or pottery but is in fact carved from an ancient tree that had to be cut down. Using furniture-making techniques, Eleanor turns the wood on a lathe to create a huge vessel that she then scorches to reveal the burrs or scars of the ancient tree in all its beauty. When she visits the V&A to see her finished work on show, alongside the museum's most celebrated sculptures in the Cast Courts, it is an honour that most artists can only dream of.

Behind the scenes at the V&A, Winston Churchill's despatch box needs attention, it's removal day for a 350-year-old doll's house, and a famouspainting by Constable is on the move.

At the V&A, a Buddhist painting is a mystery, children's art goes on show, and Josiah Wedgwood's masterpiece - the Portland Vase - is brought into the 21st century.