To a large pot of cold salted water, add the whole potatoes, cover, and bring to the boil, then reduce the heat to a low rolling boil for 30 minutes or so, until the potatoes are tender.
While the potatoes are boiling, in a big round flat-bottomed wok or large skillet or frying pan, heat the rapeseed oil or virgin olive oil over medium, then add the onions, carrots and celery and fry for around 15-20 minutes until soft and just starting to brown.
At the same time, in a separate wok/pan over medium heat, fry the beef mince until cooked, then transfer to the fried vegetables, combine well, sprinkle the flour over the mixture, and stir again to combine well, and turn the heat down to low to simmer.
The potatoes should be ready by now, so drain them, return them to the pot to reduce the moisture. When they’re cool enough to touch, peel off the skins, press them in a potato ricer, and mash them with butter and salt until creamy and smooth.
To the vegetable and ground beef mixture, add the red wine and stir in to combine well, then add the Worcestershire sauce, tomato purée, tinned tomatoes, seasoning, and fresh herbs, and combine well. Cover with a lid, turn the heat down to low, and allow to simmer for around 30 minutes or so until densely textured, stirring occasionally so the mixture doesn’t stick.
While the beef and vegetable mixture are reducing, preheat the oven to 180ºC, and finish the mashed potatoes by adding the grated cheddar cheese and nutmeg, and mashing to combine well.
Transfer the ground beef and vegetable mixture to a baking dish (around 24 cm x 18 cm in size is perfect for the ingredient amounts above; you may have a little mixture left over), then pipe the mash on top, ensuring the mixture is completely covered – or simply spread the mashed potatoes on with a spoon – and bake for 20-30 minutes until the peaks brown.
Serve immediately with buttered green peas – and bread for cleaning your plate!