The honey sandwich is the runny end of the British sweet shelf, and its whole problem is that the filling is liquid before it ever touches the bread. Honey on buttered white, closed and cut, sounds like the simplest thing a kitchen can do, but a sandwich whose only filling pours is a sandwich at war with its own crumb. Drizzle honey straight onto bread and it goes through, not slowly the way jam creeps but at the speed of a liquid finding the holes in the crust, so the defining fact of this build is that the bread has to be sealed before the honey arrives or there is no sandwich left to eat by the time anyone gets to it.
The craft is the butter doing structural work and the honey being kept off the bread. Butter spread firm and to the edges is the waterproof barrier here, not a flavour decision but a membrane that the honey sits on rather than soaks into, and being salted it supplies the single savoury note that stops a filling of pure sugar reading as flat and sickly. The honey goes on thin and onto the butter, not the crumb, because a thick pour slides out under pressure and a layer that has touched bare bread has already started its way through. Cold honey behaves; warm honey runs faster and soaks through sooner. The bread is soft plain white because the filling has no texture of its own and a chewy crust would be the only thing in the sandwich resisting a bite.
The variations put back the body and contrast a layer of honey on its own cannot bring. Banana sliced in adds fruit and bulk at the cost of a shorter life before it slumps; a scatter of oats or chopped nuts into the honey gives it the crunch it lacks; honey against peanut butter on the far slice brings salt, fat, and a bind that slows the bleed. Each deserves its own article rather than being crowded in here.