Green, who lives in a narrowboat on the Grand Union Canal, said: “There weren’t many people around me in the field and I was just wandering around when the machine beeped, so I just dug a hole.
“When I started digging it out, I saw the tips of the lobes coming through and thought it might be a bullet case.”
The gleam of gold soon put paid to that thought.
The unusual pommel was reported to Northamptonshire’s finds liaison officer Eleanore Cox, who described it as “absolutely stunning”.
“People have been detecting for many years and not found anything this magnificent – it’s a once in a lifetime find,” she said.