Bring a large pan of water to the boil. Add the stock cube and stir to dissolve. Reduce to a simmer and poach the chicken breasts for 5-10 minutes (depending on the size of the fillets) until cooked through and no pink colour remains. Remove with a slotted spoon and allow to cool before shredding. Discard the stock.
Meanwhile, heat the oil in a pan and cook the onion for about 10 minutes, until softened. Stir in the curry powder, tomato purée, cider vinegar and jam, and cook for a further 1-2 minutes. Remove from the heat and spoon into a large bowl.
Add the shredded chicken along with the lemon zest and juice, mayonnaise, yogurt, ⅔ of the flaked almonds and 1 tablespoon of the parsley and stir until well coated.
To serve, place on a serving platter and garnish with the watercress and remaining almonds and parsley. Serve with the crusty bread.
Cook's tip: turn it into a canapé. Make Melba toasts: toast sliced bread, cut off the crusts then carefully split the toast in half, horizontally, using a sharp knife. Cut each piece into 4 triangles, put on a baking sheet, and bake in a hot oven for 5-10 minutes. Top with the coronation chicken and a sprig or two of watercress