Stilton and grape is the blue cheese met by the coolest, simplest counter on the cheeseboard, and the whole sandwich turns on that one fruit. The constant underneath is the same salty crumbling Stilton, sharp and veined and difficult on its own; what makes this version itself is the halved grape worked through it. The defining fact is the burst. A grape is firm-skinned and full of cold sweet juice, and bitten against a mouthful of saline crumble it releases a small cool flood that cuts the salt and resets the palate mid-bite. The sandwich is built around that release rather than around the cheese alone, which is why a softer or warmer fruit would not do the same work.
The craft is in the cut of the grape and the bedding of a filling that wants to roll. Grapes are halved, never left whole: a whole grape skids off the cheese and out of the sandwich the moment it is pressed, and the cut face also turns the juice outward where it can reach the salt instead of trapping it behind skin. Seedless is the practical choice for the same reason the halving is, to keep the bite clean. The Stilton goes on as crumble pressed into firm butter, the butter doing its usual structural job of tacking the rubble down and rounding the brine, and the grape halves are set cut-side into that crumble so they bed rather than slide. Bread stays soft and plain because the interest is the salt-against-sweet contrast and an assertive crust would only crowd it. Pressed lightly, the halves key in and the sandwich survives a bag.
The variations stay inside the same frame of one fruit against the salty blue, and each is a different reply rather than an addition to this one. A slice of fresh pear brings water and a gentler sweetness instead of the grape's sharp burst. A bitter walnut answers the salt with tannin and crunch rather than juice. Red grapes against white shift the sweetness and the colour without changing the logic, and the dessert-grape-and-cheese plate folded into bread is the same idea read as a course. Each deserves its own article rather than being crowded in here.