The oldest Tool in my shop would be Me, I suppose. I dont collect old stuff, really, but this Fishtail below was one of those - I have to have that - deals, bought at a flea-market here. I was told it is Sheffield Steel, there are no markings on it tho, except the # 25, which can barely be seeen in 2nd photo. Pretty sure the handle is a replacement.
This spirit level isnt that old, the cover for the spirit is plastic, and the brass isnt brass. 60 centimeteres would be what, 25" in length? I found this one inside the cavity of a stone wall when I was tearing out space for sink cabinet plumbing, along with a bunch of almond husks put there by rats. The Makers mark says it was made in Switzerland, the wood Teak. Whats funny about that is, this isnt the first level I have found inside a wall. I have a much older one up in Denmark, maybe as much as 100 yrs old, also found while doing demo.