Soak chickpeas overnight or for a minimum of 8 hours, then simmer for 20 mins or until tender.
While they are cooking dry roast the cumin and coriander seeds an a hot frying pan for 2 – 3 mins, (until they start to change colour). Crush in a pestle and mortar coarsely and reserve.
Crush saffron to a powder in a pestle & mortar. Squeeze the juice of one lemon and add to the saffron, stirring well.
Season chicken. Cut peppers in half, deseeded, then cut each half into 4. Cut onions to same size.
Heat 1 tbsp oil in flameproof casserole and brown the chicken on all sides, in two batches if necessary. Remove to a plate.
Add another tbsp oil and turn heat up high. When hot add peppers and onions and cook until edges are slightly blackened, about 5 mins. Reduce heat.
Strip coriander leaves from stalks and reserve. Chop stalks finely and add to peppers, onions, with garlic, chillies, crushed spices, chickpeas and rice. Stir well and season.
Combine lemon and saffron mixture with stock and wine and pour into casserole, stirring well. Cut remaining lemon into slices and push into liquid. Scatter in olives and place chicken on top.
Cover and put into a preheated oven, gas 4, 180 C, for 1 hour or until rice and chickpeas are tender. Serve scattered with coriander leaves.