The day before you start, soak the beef bones in water until the marrow is soft enough to push out of the bones. Soak the bone marrow in water for 24 hours, changing the water four times in total, then drain and cut it into thick slices.
For the filling, dredge the beef shin pieces in the seasoned flour.
Heat the beef dripping in a large lidded saucepan and fry the beef shin for 4-5 minutes, or until browned all over. (You may need to do this in batches.) Remove the beef from the pan and set aside to drain in a colander.
Add the onions to same saucepan and fry for 8-10 minutes, or until golden-brown. Add the red wine and boil the mixture until the volume of the liquid has reduced by half. Add the beef stock and bouquet garni and season, to taste, with salt and freshly ground black pepper.
Bring the mixture to the boil, then reduce the heat until the mixture is simmering, cover with a lid and simmer for one hour. After one hour, remove the lid and simmer for a further 15 minutes, or until the beef is tender.
Spoon the mixture into a large bowl and set aside to cool.
Meanwhile, for the sauce, heat the chicken stock and beef stock and tomato juice in a saucepan until boiling. Reduce the heat until the mixture is simmering and continue to cook for 1-2 hours, or until the volume of the liquid has reduced by three-quarters. Skim off any scum if necessary. Set aside.
Meanwhile, heat the shallots and red wine in a saucepan until boiling. Reduce the heat and simmer for 1-2 hours, or until the red wine has evaporated.
Strain the stock mixture through a sieve into the saucepan with the shallot and red wine mixture in it. Stir until well combined and season, to taste, with salt and freshly ground black pepper.
For the pudding, grease a 1.75 litres/3 pint pudding basin with butter.
Stir the self-raising flour, suet, water and salt in a bowl until the mixture comes together as a dough.
Turn out the dough onto a lightly floured work surface, pinch off a quarter of the dough and set it aside.
Roll out the remaining dough into a 25cm/10in circle. Transfer the rolled pastry to the prepared pudding basin and mould it to the sides of the basin (leave the excess pastry hanging over the edge of the basin). Set aside.
Roll the remaining dough out onto a lightly floured work surface until it is 1cm/½in thick and 2.5cm/1in wider in diameter than the top of the pudding basin. Set aside.
Spoon the filling mixture into the pastry case
Place the pastry lid on top of the pudding basin, moisten the edges with water, and press down to seal.
Wrap the pudding basin in a double layer of aluminium foil and secure with string. Place it on a heatproof plate and transfer to a large pan. Add enough boiling water to reach halfway up the sides of the pudding basin, cover the pan with a lid and steam for 1½ hours, topping up the water level as necessary.
For the mash, cook the potatoes in a pan of salted boiling water for 15 minutes, or until tender. Drain and return to the pan, over the heat for a few seconds, to drive off any excess moisture.
Mash the potatoes well then add the butter and cream and beat to a smooth purée. Season, to taste, with salt and freshly ground black pepper.
To serve, carefully remove the aluminium foil from the pudding. Place a serving plate on top of the pudding, turn the pudding upside down and gently lift off the pudding basin.
Just before serving, add the bone marrow to the sauce and heat until the bone marrow has melted and the sauce has warmed through.
To serve, place one slice of pudding onto each of five serving plates. Spoon the sauce over the pudding and serve the mash alongside.