E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
George a Green.
As good as George a Green. Resolute-minded; one who will do his duty come what may. George a Green was the famous pinder or pound-keeper of Wakefield, who resisted Robin Hood, Will Scarlett, and Little John single-handed when they attempted to commit a trespass in Wakefield.