Lorne, egg, and tattie scone is the Scottish breakfast roll built around three distinct elements rather than one filling. Lorne is square sliced sausage, a flat slab of seasoned beef and pork with a fine close texture cut from a loaf rather than a link; a tattie scone is a soft, flat, griddled potato bread; and the egg is fried with a yolk that runs. Stacked together in a morning roll, these are not one component with garnish but three things each doing a separate job: the Lorne is the savoury slab, the tattie scone is a soft starchy bed, and the egg is the wet element that binds the other two. The defining fact is that this is a built sandwich of three breakfast parts assembled into one fold, the full Scottish plate compressed into a roll.
The craft is heat, order, and managing the yolk. The Lorne is cut to the width of the roll and griddled hard so the flat faces brown and the slab firms enough to lie flat without sliding. The tattie scone is fried until it is hot and lightly crisp at the edge but still soft through, then placed where it can take the yolk, because its job is to be the absorbent layer that catches the egg before it reaches the bread. The egg is the last and most fragile decision: it is set so the white is firm and the yolk still loose, and it goes in directly against the tattie scone so the roll does not turn to mush. The roll itself is a soft floured morning roll, yielding enough to compress to a thick stack but sturdy enough to hold rendered fat and yolk for the few minutes it survives, with butter as the bridge between the salt of the Lorne and the wheat. A sauce, brown or red, goes inside in a measured stripe so it cuts the fat without running.
The variations are mostly about which breakfast parts are swapped in or out of the stack. Bacon stands in for or joins the Lorne. Black pudding adds a third savoury slab and its own crumble. Square sausage with egg alone drops the tattie scone for a two-part build. The wider Scottish and full-breakfast roll shelf, the haggis roll, the Ulster fry, the bacon roll under every regional name, is each a different combination on the same morning logic and deserves its own article rather than being crowded in here.