Wensleydale and cranberry is defined by the fruit, not the cheese. Wensleydale on its own is a mild, crumbly, faintly sweet Yorkshire cheese with very little assertiveness, which is exactly why this pairing exists: a sharp, tart cranberry sauce or a scatter of dried cranberries gives the sandwich the high, acidic note the cheese cannot supply itself. The defining move is the counter. Take the cranberry away and you have a quiet white-cheese sandwich; put it back and the whole thing sharpens into focus, the tartness lifting the mild dairy and the cheese rounding off the fruit's edge.
The craft is balance and moisture control. The cheese crumbles rather than slices cleanly, so it is broken into a layer thick enough to read against the fruit, not shaved so thin it disappears under it. The cranberry is the variable that needs managing: a wet cranberry sauce will bleed into the crumb and turn the sandwich soggy, so it is spread thin over a buttered slice that has been sealed against it, or dried cranberries are used instead so they bring tartness without water. The bread is plain and soft because both components are gentle in texture and an assertive crust would argue with a filling whose entire appeal is the clean contrast of crumbly and tart.
The variations move along the sweet-savoury line the pairing already sits on. A little Wensleydale with apricot or with apple keeps the same mild-cheese-and-sweet-fruit logic; the plain Wensleydale sandwich strips the fruit out and lets the cheese stand alone; the wider British cheese-and-chutney builds do the same trick with a different cheese and a different preserve. Each deserves its own article rather than being crowded in here.