Christmas is a busy time in Billund. While the North Pole is Santa’s domain, this small Danish town is the centre of the plastic brick universe. For Billund is the home of LEGO and, in December, its 4,000 employees are engaged in the intricate logistics of ensuring children in 142 countries get their festive fix. Since the company was founded in 1932 it has been based in Billund – and has literally built most of it. LEGO built its international airport, turned the former hamlet’s town hall into an early HQ and put up its first theme park here. Now it is developing a new, bigger base, known as the LEGO Campus, which is due for completion in 2022.

The town and its most famous firm are so closely linked that LEGO artefacts are even buried in foundations. Construction workers recently dug up moulds used to make early bricks – which had been buried to ensure no one would copy them.

While many of the firm’s facilities are open to the public and employees, one special place remains a top secret. Until now. Behind a secret door in the LEGO Ideas House museum – only open to employees – stairs lead down into a basement.

The CCTV cameras and electronic access system are the only signs that something special is stored here in the subterranean gloom.

The secure door leads to a chilly, cavernous room, filled with floor-to-ceiling mobile metal shelves, each stuffed with boxed sets and figures. This is LEGO’s secret vault. It houses arguably the most exclusive toy collection on the planet.

It’s probably easier to get into Santa’s grotto than it is to get into the vault. Only a handful of people are allowed inside to see the collection, which includes one of every LEGO set ever released to retailers, dating back to 1966. A selection of even older LEGO products is stored here too.

Daily Express's Nick Harding with first Lego set

Daily Express writer Nick Harding with the first ever LEGO set from 1961 (Image: Tim Clarke/Daily Express)

No one is allowed in unaccompanied and the few LEGO devotees lucky enough to be invited have only been allowed to stay for 30 minutes. The Daily Express was given an exclusive tour.

“Grown men have come in here and wept, because they are overcome with the nostalgia of seeing the toys they loved in their childhood,” explains company historian and guardian of the vault, Signe Wiese.

Each Christmas sees the latest additions to the 7,500-piece collection consigned to the vault.

The 2019 section of the racks now includes sets from LEGO’s Hidden Side range. These use digital augmented reality to add a new dimension to the plastic brick and mark a new era. The contrast between these products and the very first ones illustrates toy evolution.

The racks provide a timeline, including the first products with moving parts, batteries and computer coding.

The vault’s very first exhibit, and LEGO’s very first set, is a priceless large, heavy LEGO Town Plan from 1961. Still boxed, the complete set came with a wooden base and two colours of brick – red and white.

Signe Wiese with box sets, including Harry Potter

Signe Wiese with box sets, including Harry Potter and Star Wars tie-ins (Image: Tim Clarke/DailyExpress)

Notably there were no instructions. Early LEGO users were given picture guidelines and encouraged to use their imaginations. Instructions were only included from 1963.

“It was natural step,” explains Signe. “When you follow building instructions you learn lots of things and when you free-build you learn different things. It was a way of us suggesting that you can do different things.”

The very first plastic LEGO bricks were hollow, which meant that the structures children built with them were unstable and liable to fall over.

Perhaps the biggest milestone for the toymaker came in 1958 when it developed a structure of tubes within the bricks that clicked on to external studs. This ensured that the bricks stayed together yet could be separated easily.

Lego call this “clutch power”. The design was granted a patent in 1961 for 24 krone (£2.70) and has earned the toymaker billions of pounds since.

Although the original patent for the little bricks ran out in 2011, the company protects its name and LEGO brands such as Hidden Side, Ninjago, Minifigures and Lego Friends, with trademarks.

A vintage duck toy

A vintage duck toy at LEGO’s Danish HQ (Image: Tim Clarke/DailyExpress)

While there is now nothing to stop copycats, LEGO is confident any attempt to emulate it will be inferior.

Signe explains: “LEGO bricks are designed to within 0.004mm accuracy to ensure they fit perfectly. You can take a brick from 1961, and it will still seamlessly connect with a brick from today.

“Making bricks of that quality is not as easy as it looks.”

The vault includes several pieces that marked LEGO milestones, including the first LEGO wheel from 1962 and the first range of figures from 1974. The latter were too big to be played with alongside its bricks so designers went back to the drawing board and, in 1978, launched the smaller Minifigures that children collect today and that are characters in the hit LEGO films.

The addition of LEGO figures also fundamentally changed the way children played with the toy.

“By adding people, we added the ability to role play,” says Signe. “The early figures had generic faces to encourage children to use their creativity and imagination.”

The vault houses rarities such as the first LEGO Star Wars set, the first LEGO Harry Potter tie-in and the first Bionicle products from the early 2000s. These are all now worth huge sums of money to collectors.

Signe Wiese, Lego Culture Mediator

Signe Wiese, Lego Culture Mediator (Image: Tim Clarke/DailyExpress)

Signe reveals that the advent of the hugely successful Star Wars range almost didn’t happen because of the company’s strict anti-violence policy.

She explains: “The first Star Wars products came out in 1999. The idea was pitched by the US CEO at the time but there was a big internal debate about making a product with ‘war’ in the title.

“We are careful about what we introduce children too and have a non-conflict policy.

“It took a couple of years to finally decide to go ahead and the way we handled the conflict issue was by adding LEGO humour to the sets.

“The Minifigures, for example, are funny. There is nothing threatening about a Darth Vader Minifigure. We also made sure any weapons were either really old, like swords, or futuristic.”

Several new additions to the vault this festive season hark back to Christmases past. Bestsellers are expected to include the space race-inspired Deep Space Rocket and Launch Control, the Harry Potter Hogwarts Clock Tower and the Star Wars Boost Droid Commander.

LEGO has a large adult fanbase, who call themselves AFOLs (adult fans of LEGO). Each year the company develops several intricate sets specifically for the adult market and it is these fans who most want to take a peek inside the vault.

And for them, the vault’s Holy Grail is a 33in Statue of Liberty from 2000.

“Fans go nuts for it,” says Signe. “It was a limited product and hard to get hold of. It was the biggest set ever launched at the time with 2,882 bricks.”

LEGO, which celebrated its 60th anniversary last year, adds new products all the time and they take years to develop.

Space in the vault is limited and there are only three rows of shelves left to fill, so there are plans to move the collection to a secure facility in the new campus.

Meanwhile, the company is looking to the future and has developed a new type of sustainable plastic derived from sugar cane. LEGO, it seems, never goes out of fashion.