To Put a Spanner in the Works

This British idiom means to cause a disruption, obstacle, or unexpected problem that interferes with a plan or process. Imagine a well-oiled machine humming along smoothly — then someone tosses a spanner (wrench) into its gears. Suddenly, everything grinds to a halt.

Used in context:

• “We were ready to launch the new website, but the server crash put a spanner in the works.”

• “Her last-minute cancellation really threw a spanner in the works for our weekend plans.”

American equivalent: “To throw a wrench in the works.”

Whether it’s a technical glitch, a surprise decision, or a twist of fate, this phrase captures the frustration of plans gone awry - with a mechanical metaphor that’s satisfyingly vivid.