Bring the stock to the boil, stir in the saffron and set aside until needed. Trim the rind and fat off the bacon and cut it into 1 cm (½ in) strips. Cut the chicken into 2.5 cm (1 in) cubes.
Heat 1 tablespoon of olive oil in a large, deep pan with lid. Add the bacon and chicken and cook over a medium heat for 5 minutes, or until they are lightly browned, turning the pieces frequently. Then remove them and set aside.
Add the remaining oil to the pan, then add the onions, peppers and garlic, and cook over a low heat for 10-15 minutes until they are softened but not coloured.
Stir in the tomatoes and bring the mixture to the boil. Then reduce the heat to medium and continue to cook for a further 9-10 minutes, stirring frequently, until some of the liquid from the tomatoes has evaporated and the mixture has thickened slightly.
Stir the rice into the pan, add the chicken and bacon, the stock and a pinch of salt and bring to the boil. Then reduce the heat to low, cover the pan with a tight-fitting lid or foil and simmer for 25 minutes without looking.
Meanwhile, clean the squid and cut them into quarters lengthways. Scrub and debeard the mussels, discarding any that are open or damaged.
Stir the squid, mussels and peas into the rice and cook the paella for a further 10 minutes, or until the rice has absorbed all the stock and the mussels have all opened (discard any that do not open). If the mixture sticks to the pan, add the white wine, if using, or a little water.
Season with plenty of black pepper, then add the peeled prawns and mix them in gently with a fork. Scatter the whole prawns on top, if using, and cook for 3-4 minutes more until all the prawns are heated through.
Sprinkle the parsley over the paella and serve it with lemon wedges on the side, if you like.