Peel and cut the Floury Potatoes (Maris Piper) into even chunks and place in a pan of cold water; add a generous pinch of Fine Salt, bring to the boil and simmer until very tender, about 15–20 minutes.
Drain the potatoes well, return to the pan off the heat and mash with a good knob of Unsalted Butter and a splash of warmed Whole Milk until smooth and creamy; season to taste with Fine Salt and Black Pepper. Keep warm.
Heat a little Neutral Oil in a heavy frying pan over medium heat. Add the British Pork Sausages and cook, turning occasionally, until evenly browned and cooked through, about 12–15 minutes. Transfer to a plate and rest under foil.
In the same pan, add a little more Neutral Oil and a knob of Unsalted Butter and reduce the heat to low. Add thinly sliced Onions and cook gently, stirring occasionally, until softened and caramelised, about 12–15 minutes.
Sprinkle over the Plain Flour and cook for 1–2 minutes to lose the raw taste, then gradually stir in the Beef Stock to form a smooth gravy.
Add a dash of Worcestershire Sauce, bring the gravy to a simmer and cook until thickened to your liking; adjust seasoning with Fine Salt and Black Pepper.
To serve, pile a generous scoop of mash on each plate, top with the sausages and spoon over plenty of onion gravy. Enjoy immediately while hot.
