Mine is definitely 1832, I've seen it now, although I cannot liken it well enough to the small black and white section of the Sheffield centre section of an 1832 Sheffield map that I have on my hard drive which I downloaded some years ago. As that one is not sharp enough. But I suspect it is just a small section of mine and a photocopy that has been scanned in on a low resolution.
Does anyone know if the original prints of such old maps went brown over time? If so I think mine might be an original print. It looks extremely old and has benefited from being ptotected for some time behind glass.