No-one has explained the word "slot" yet.
Machfitt Shop Slot?
Slot Machfitt Shop?
Shop Slot Machfitt?
Googling returns nothing useful; Machfitt flooring as already mentioned (doesn't explain shot; or shop particularly well).
There's no sign of Machfitt in either the Domesday book or 1911 census (or earlier). Could Machfitt be German, i.e. this was something that came over during or after WW1 or 2? Again, google is unhelpful.
If it were not stamped, I would have suggested it was an engineer's exercise, judging by the lines drawn on the teeth; I would definitely think it was handmade, but as to its purpose or maker, it would seem the required information is not yet online...