Pointy-chinned (and formerly bearded) English football pundit.
A figure who most football fans love to hate and disagree with. Chairman of Coventry City football club.
Popular target of British impressionists due to his distinct vocal style.

Inexplicably became a synonym for disbelief when I was a kid in the 70s. If someone told you a preposterous story you'd stroke your chin and say slowly "Jimmy Hill" or "Jimmy".