The honey roast ham sandwich is a savoury sandwich that happens to be built on a sweetened meat, and the distinction matters because it sits next to a shelf of sweet honey sandwiches it has nothing to do with. The lead here is the ham itself: a cooked ham glazed with honey and roasted so the sugar caramelises into a dark, sticky, faintly bitter crust on the outside of the joint. That glazed edge is the whole point of choosing this ham over a plain one. It is not a sweet sandwich and it is not a plain ham sandwich either; it is a ham sandwich where the meat arrives already carrying its own contrast, salt and cure underneath, burnt-sugar lacquer on the surface, so the sweetness is structural to the filling rather than spread on as jam.
The craft is letting the ham lead and not doubling the sugar it already has. Honey roast ham is sweeter and softer than a plain boiled ham, so the counterweight is pulled the other way: English mustard rather than a fruit chutney, because the sandwich already has its sweet note and what it needs is heat and sharpness to stop the glaze cloying. The ham is carved thick enough that the caramelised edge shows in the cut and is not lost among pale slices, then laid so each bite gets some of that crust rather than all interior. Butter bridges the salt of the cure to the wheat of the bread and seals the crumb against the slight moisture the glazed meat carries. The bread is soft and plain so it frames the ham rather than competing with a filling that is already doing two things at once.
The variations stay on the ham counter and change the partner. Honey roast ham with mustard is the sharp default; with a mild cheese it becomes a gentler ham and cheese where the glaze does the work pickle usually does; with a fruit chutney it tips deliberately sweeter for those who want it. Each deserves its own article rather than being crowded in here.