grey pound

(British) the perceived purchasing power of Britain’s Black and Asian minorities as a group.

(chiefly, UK, Canada, Australia, idiomatic) The collective political, economic, and social influence of senior citizens, especially when they are mobilized by a common interest.

(UK) The business generated by providing goods and services to the gay community.

(Britain) A person in receipt of an old age pension, a senior citizen.

A British idiom expressing high confidence that something is true or likely to happen, essentially saying you would bet a pound against just a penny, meaning the odds are overwhelmingly in favor. Used to emphasize certainty about a prediction or claim. More colorful than simply saying almost certainly but functionally equivalent. The asymmetric financial metaphor makes the confidence tangible and specific.