Just to update re the spot on my vintage Willis, the stain is gone - yay - but the area is a bit dull. I'd like to restore the allover luster to the bag and blend the area that was stained but not sure what to use that will darken the leather as little as possible. It's now a matter of texture - that bit is duller than the surrounding area - so I think it just needs some non-staining moisturizer.I would try vinegar and a magic eraser first. After that, if it is still there, you could try conditioner to see if it will blend it. The conditioner I use most often is Leather CPR followed by Blackrock Leather n Rich. It's a good idea to buy these conditioners for maintenance of your vintage Coach items anyway. If none of that works, then a bath is in order. You can read through this thread to see how to give your bag a bath.
I keep reading conflicting advice re Coach cleaning/conditioning products (they contain silicone?). Would like to use something really light to keep the look of the bag as unchanged as possible.
Thanks as always.