Inside every museum is a hidden world, and now, for the first time, cameras have been allowed behind the scenes at the world-famous Victoria and Albert Museum in London.

Only a small part of the two million wonders in the collection are on display to the public. But in this new series we go behind closed doors to explore all the treasures of art, design and performance the museum has to offer.

This week, we meet curators and conservators trying to preserve some of the finest examples of craftsmanship in the world.

Deep in the museum stores, curator Keith is trying to breathe life into an object of extraordinary craftmanship – an original Stormtrooper costume from the Star Wars sequel The Empire Strikes Back, from 1980. He's hoping to exhibit the costume in a refresh of the V&A's Theatre and Performance Display. But when he and conservator Susana unpack the moulded-plastic body parts, a key piece is missing – the Stormtrooper's helmet.

Unable to display the costume without the helmet, Keith contacts a group of prop-makers who specialise in making replicas of movie costumes. The prop-makers agree to make a replica of the original helmet, using the exact techniques pioneered by the Star Wars costume department in the 1970s. But the challenge for Keith's prop-makers is to turn this box-fresh helmet into an authentic match with the original decades-old costume.

Meanwhile, two of the largest galleries in the museum, the Cast Courts, are undergoing a renovation. These galleries are home to one of the world's largest collections of 19th century hand-made casts - replicas of some of Europe's finest sculptures. As few people then could afford the luxury of travel, art works could be brought to them with these painstaking replicas. Now it's the job of senior sculpture conservator Victor to give these precious casts a facelift.

The final part of the epic renovation is cleaning a piece representing the Assumption of the Virgin, made in 1890. This plaster cast depicts the Virgin Mary ascending to heaven surrounded by angels. It's a perfect plaster copy of one of a number of 14th-century sculptured panels made for the exterior of the Notre Dame cathedral in Paris. Now the plaster cast will be given its first deep clean since it was made 130 years ago.

The importance of these fragile replicas is brought into sharp focus with news of a terrible fire at Notre Dame. Although many artefacts are destroyed there is relief that the original cast of the Assumption of Virgin has been spared.

The news highlights the importance of preserving the V&A's delicate cast. But Victor and fellow conservator Adriana discover a crack in its structure, that could prove fatal. Over hours of careful conservation, the team work on supporting the fracture - but the real test will be when they try to hang it back on the gallery wall.

In the Rock and Pop archive, curator Vicky is examining a photograph donated after the V&A's David Bowie Exhibition. It's a rare print, known as ‘David Bowie is watching you', taken in 1973 as part of a series of photos by photographer Brian Duffy to become the album cover for Aladdin Sane. The picture was donated by the photographer's son Chris. Vicky wants to know more about the print and invites Chris to the museum. Chris remembers visiting the photoshoot when he was a teenager, and meeting David Bowie.

In paper conservation, senior preservations conservator Simon is dealing with a very different kind of photograph – a 65-metre-long Victorian photograph of the medieval Bayeux Tapestry. This unique photograph was commissioned by the British Government in 1871 and was one of the V&A's first interactive exhibits, displayed on a moving roller so audiences could spool through the panorama of the battle.

The last time it was on display was over 100 years ago. But years of manhandling have taken their toll. Now, the rolled-up photograph has been summoned to be part of a new V&A exhibition, filled with new images by legendary fashion photographer Tim Walker, inspired by objects from the museum's collection. But first conservator Simon needs to assess if the fragile piece is robust enough to be displayed again.

In the Rapid Response Department, curators Corinna and Johanna feel there is one important everyday object missing from their 20th-century collection. They have been offered a very British piece of graphic design – a road sign, made in 1961 by graphic designer Margaret Calvert. Before collecting the sign, they visit Margaret at her home, filled with familiar road signs…

We also follow fashion curator Oriole, who alongside colleague Susan, is on a mission to acquire a piece representing the best of contemporary British craft. They visit fashion designers Justin Thornton and Thea Bregazzi, known as Preen, at their workshop. Oriole and Susan have the difficult task of choosing one single piece to represent the designers.

Inside every museum is a hidden world, and now, cameras have been allowed behind the scenes at the world-famous Victoria and Albert Museum in London.

Only a small part of the two million wonders in the collection are on display to the public. But in this series, we go behind closed doors to explore all the treasures of art, design and performance the museum has to offer.

We follow experts and conservators at work in this treasure trove of the nation's favourite objects, as they breathe new life into fragile marvels, uncover hidden stories and battle to keep the past alive.

In this instalment, we join Catherine Sargent as she prepares a new exhibition devoted to cars. She must ensure these large objects are displayed at their best, but as with all the vehicles arriving on loan from around the world, it's imperative that each one is moved into the museum without a scratch.

One of the largest and trickiest to transport is an extraordinary 1962 Chevy Impala, known as ‘Tipsy', arriving from Los Angeles. It's a unique car, that's been painstakingly customised to turn it into a ‘low-rider'.

With its low-slung chassis, gleaming paintwork and personalised motifs, the car was a six-year labour of love for owner Tomas Vasquez. Seeing Tipsy up close before it's moved into the museum, Catherine has some concern that it will be a tight squeeze getting it into the exhibition space. And with the added pressure of the owner flying into the UK to give his pride and joy one last loving polish before the opening, she has to ensure the move runs without a hitch.

Meanwhile, some of the finest of the V&A's one-off objects are in the Rosalinde and Arthur Gilbert collection, and curator Alice Minter is choosing a selection of her favourites to be displayed in an upcoming exhibition that will tour around the world.

She's found one rare masterpiece in storage that she thinks is going to be the star of the tour. It's a tabletop decorated using a technique known as ‘micromosaic', in which thousands of individually coloured pieces of glass are set into a pattern producing an effect like a painting. The process of making a micromosaic is so intricate that this tabletop would have taken a craftsman years to finish.

But Alice discovers that her beloved table is going to struggle to make the tour, as conservators have discovered cracks and swellings on the surface. X-rays reveal the full damage inside, with holes and corrosion making this object too vulnerable to move anywhere. Conservator Mariam makes the brave decision to conduct an experimental operation to save the tabletop from falling to pieces. She injects grout into the micromosaic, in the hope of gluing together its internal structure. Alice hopes this life-saving surgery will give this masterpiece a chance of going on display and being admired by the public.

Other rare survivors are unearthed in the Rock and Pop archive, as curator Vicky picks out the latest acquisitions for the V&A's collection of objects relating to The Beatles. She's interested in some of the animation cels from the groundbreaking movie Yellow Submarine. One of the film's animators, Malcolm Draper, has been invited in to explain how they were made. It's important for Vicky to understand the whole story of these objects to help keep alive the craft of drawing animation cels by hand.

Over in textiles conservation, a rare men's kimono is being repaired so it can be displayed in an upcoming exhibition. Worn by a samurai feudal lord in the late 18th century, Elizabeth-Anne Haldane has discovered rips in its fine inner silk lining near the waist that may have been made by a samurai sword. To have any chance of displaying the chequerboard-patterned kimono on a mannequin, she must delicately dye a patch and sew it into the torn areas.

In the jewellery galleries, conservators and curators are excited to take delivery of a rare buried treasure – a medieval jewel discovered in a field in Northamptonshire by a metal detectorist. The extraordinarily rare ‘cluster brooch' is made of gold and set with diamonds and a reddish stone called a spinel.

With only seven of its type ever found in the world, this is a special piece. Experienced conservator and gemologist Jo Whalley has the task of giving it a deep clean.

Using a mixture of spit and polish (as saliva contains enzymes that help to degrade soil and dirt), Jo must delicately remove the earth embedded in the jewel to reveal once more the full beauty of this miniature treasure.