In preparing the cabinet for its new home, I took the vacuum cleaner to it, wiped it down with a soft towel and then again with furniture polish.
Horn cabinet? Or, did the previous owner purchase a Horn tray that just happened to fit in the drawer?
A quick Google search found a few photos of older Horn cabinets with keyholes similar to the ones on this cabinet. It lacks an airlift that the new Horn cabinets have. However, of my machines, the Singer 403A is the only one that fits into the cabinet hinges and the cut out. So, is it safe to say that the cabinet is intended for a standard vintage, pre-electronic machine and therefore pre-dated the need for an airlift - late 1950s/1960s?
If it isn't a Horn, what is it?