Here it is!
The fit around the barrel band was so good that it wouldn't budge and seeing as the rifle seemed to be in near original condition (for a 35 year old rifle) I didn't force the issue.
I think the previous owner took this claim seriously as the barrel was filthy 
but the bolt and inside the receiver, from what I could get to, was remarkably clean. In the end, I just wiped some oil on just to make myself feel better about the lack of success at stripping it. The barrel came clean very quickly with a couple of goes with the pull through. Speaking of the bolt, I really like the design of the cocking handle. It slides in and out to enable you to lock the working parts to the rear, which great. 
No last round hold open, but as it's only a 7 round mag (standard Marlin one) I think I can manage to count to 7!Am I happy? Very, very happy! :shakeshout: Just need to give it test run.
I haven't actually measured the barrel but it should be an 18 inch barrel and 37 inch OAL.