· Behind the scenes
How we built the vault door
Four hundred kilos of steel, a dial that only turns one way, and why it took us three tries.
The vault door in The Vault weighs four hundred kilos and opens with one finger. Getting there took us three versions and most of a winter.
Version one: too heavy
The first door was solid steel and looked wonderful. It also needed two people to swing it, which is two people too many in the last minute of a game.
Version two: too clever
We hid the mechanism in the hinge. Players loved it, until the hinge needed oiling every four games.
Version three: the one you play
A steel skin over an aluminium frame, a counterweight in the wall, and a dial that only turns one way, so nobody can spin their way to the answer. It has opened more than nine thousand times since.