Hi, thanks for all you replies.
Jim, 1870's would fit very well with what I was hoping as the man I believe it is was in his 70's then. I had wondered whether it might be his son (who had the same name) rather than him but the son wasn't born until 1831, so judging by the age of the man in the photo if it's from the 1870's I think it must be the father.
Thanks your restoration Bill. You've done a great job, especially with so little detail in the face to work with. It's much appreciated.
Thanks for your suggestions on the label Tony. Do you think this was a label placed on the photo by the photographer at the time or something that might have been added much later by a relative? I was a bit surprised the label was on the front. I think the first line may say Huck as that was the man's surname. I didn't have a clue about the rest though but was hoping there may be a date in there somewhere. A filing code makes a lot of sense though as it does seem to have several numbers or letters or whatever.
Thanks again to you all, Paul.