[Boyd C-F]

After having a play with both a leather strop and a waxed hemp thread under the work bench while drawfiling (I don't have a fancy metal scraper) I did notice that the strop stops any horizontal rotation the file may do across the surface. While this is usually not that bad while drawfiling I can imagine that using scraper like the one pictured above, this would be a bit of a problem.
It also helped in keep the pressure constant as I moved down the work.
If one side lifted higher while making a stroke it was immediately obvious from the pressure on my finger.

A couple of possibilities for the purpose of the red strop in the image posted above.

Although it could just be a rag used to daub up the blood of the craftsmen as they poke themselves on bits of sharp metal...


Cheers

Boyd