Ive just called the old guy that lived here. He's coming to make sure its what he thinks it is but yes unwashed it appears that your right it is indeed a roller minus the handles.
Weve been wracking our brains all night to think what it might be, first thought was cess pit but knew we didnt have one, second was bomb, just wasnt sure.
We were going to have a word with the fire station over the road and ask them their opinion.