Buckley's Chance Meaning

(Australia, idiomatic, informal) A very small chance; no chance at all.

Example: 1936, Andrew Barton ("Banjo") Paterson, The Shearer′s Colt, Gutenberg Australia eBook #0603461h,
  "So he has a chance," said Connie. "Buckley's chance, the way his luck is. Fell out with his girl he did, and lost his job, and now 'e's goin' to lose 'is life. The unluckiest man that ever lived."