Preheat the oven to 180C/160C Fan/Gas 4.
For the lamb, rub the oil into the lamb shoulder and season with salt and pepper. Place the lamb into a deep baking tray, surround it with the garlic, herbs, red wine and beef stock and roast in the oven for 30-40 minutes.
Reduce the heat to 120C/100C Fan/Gas ½, cover the lamb with aluminium foil, and continue to cook for 4½ hours. Remove and leave to cool. Once cool enough to handle, shred the meat.
Heat a large casserole pan until hot, add the pancetta and fry for 3-4 minutes, or until the pancetta softens and the fat starts to melt.
Add the olive oil and then add the onion and garlic and fry gently for 1-2 minutes, or until softened. Add the carrots and celery to the pan and cook for another minute.
Stir in the shredded meat, then add the tomatoes and bring to the boil. Reduce the heat and simmer for 5 minutes.
Stir in the tomato purée and cook for a further minute. Add the red wine and simmer until the volume of the liquid has reduced by one quarter.
Add the lamb stock and return the ragù to the boil. Season with salt and pepper. Reduce the heat and simmer for 30- 40 minutes, or until the ragù has thickened. Finish with the fresh basil.
For the gnocchi, preheat the oven to 180C/160C Fan/Gas 4.
Lightly score or prick the potatoes. Spread out the salt on a baking tray to make a bed of salt and sit the potatoes on top. Bake in the oven for 45 minutes to one hour, or until tender. (You can do this at the same time as the lamb is roasting.)
Allow the potatoes to cool until comfortable enough to handle. Cut in half and spoon the cooked potato out of the skins.
Finely mash the potato or put through a potato ricer. Add the flour, Parmesan and egg yolk. Season with salt and pepper and mix well. Keep mixing until the potato forms a dough.
Working on a lightly floured surface, divide the dough into four. Roll each quarter into a sausage shape about 20cm/8in long and cut into 2cm/1in pieces. Shake off any excess flour.
Heat a large saucepan of boiling salted water and add the gnocchi cook for 1-3 minutes or until they start floating on the top of the water and drain. Drizzle with a little olive oil.
To serve, stir some of the ragù through the gnocchi. Put the gnocchi in a serving bowl with freshly grated Parmesan of top.