It's not the beer – although John has been known to enjoy an odd glass – it's what is under the ancient stone floor in the Westminster Arms.
Eighteen years ago John stood in the pub's basement bar with friends – including the late Leeds Central MP Derek Fatchett – and while fiddling with his wedding ring, dropped it.
It rolled across the floor and down a crack between the flagstones and floorboards
The two MPs, and the then landlord, carried out a fingertip search but with no luck.
Mr Battle has returned to the pub at least six times with magnets, metal detectors, torches and coat hangers to try to find the ring.
But the pub subsequently changed hands and the gaps between the flagstones and floorboards were filled in, forcing him to reluctantly concede that the ring will never be found.
He said: "I used to fiddle with the wedding ring and sadly it fell down the crack. I have never had another one since then. I thought 'well I know where it is – it's in the floor of the Westminster Arms'.
"We tried magnets, we tried weights, we tried torches. But you can't take the floor up. I'm convinced it's sealed under the floor."
Mr Battle – who is standing down as Leeds West MP at the next election – said his wife took news of the ring's loss well: "Mary is the coolest, practical person on earth."
He added: "When they renovated Westminster Hall in Parliament, they discovered chairs which dated back to Henry VIII.
"I would like to think that in 300 to 400 years time when they knock down the Westminster Arms they will finally find John Battle's wedding ring."