A quick roadside cache and dash in Back Lane Herriard.
The cache was placed thinking that the structure in the middle of the field was the Herriard ROC bunker, I now know that to be elsewhere.
I guess this structure is just another air raid shelter such as the ones immediately behind the hedge and at Back Lane/The Avenue junction.
You are looking for a money container in the hedgerow on the road side, bring your own pen.