The key snapped in the lock. Leave the stub where it is.

A key does not snap because you were rough with it. It snaps because it had been bending for months. Every time a lock is stiff, the blade flexes a little at the shoulder, and brass work-hardens as it flexes. One cold morning the crystal structure has had enough and the blade parts, usually at the first cut.

Why the stub is easy to get out — until it isn’t

The half still in the lock is sitting in the keyway with all six pin stacks resting on it. It is not gripped. It is held by friction and by the pins pressing down, and a broken-key extractor is a thin barbed shim that goes down beside it, catches a cut, and draws it back out. Ten minutes, no damage, and we can usually cut you a replacement from the half you are still holding.

What makes that impossible:

• Pliers. They only reach a stub that is already proud, and the first thing they do is round off the edge an extractor needs.
• Superglue on a matchstick. It works in videos. In a lock it glues the stub to the wafers.
• Turning it with the other half. The two faces are a fracture surface, not a joint. They cam over each other and drive the stub deeper.

What it costs

Extraction is inside the first hour of a lockout callout — £69, no call-out fee, and that includes cutting you a new key from the piece in your hand if the bow half survived. If the stub has been chewed we may have to pull the cylinder, which is a £95 euro cylinder change, and if it is a mortice lock the case has to come off the door.

The number worth remembering is the difference: about £69 if you ring straight away, and about £145 if you spend twenty minutes on it first.

The lock was telling you

A key that has to be jiggled is a lock that has moved. Usually the door has dropped on its hinges and the bolt is no longer meeting its keep square, so you are turning against the frame rather than against the springs. That is a hinge adjustment, not a new lock, and it is the cheapest thing we do.