I could very well imagine, that at least the acidic part of the signature McClelland tin note is due to a bit of vinegar being added at some point in the process, but I don't know it for a fact. What I do know is that this particular aroma does not translate into the smoke and especially the aged stoved Virginias of McC (Blackwoods Flake, St. James Woods, Christmas Cheer) are some of the best tobaccos I have ever tried.
So if anyone discards these awesome blends because of the tin note it's good news, because there is more for me