Heat the oven to 200C (180C fan)/390F/gas 6.
Using your fingers, and working from the neck end down, loosen the skin from the chicken breast. Finely chop the anchovies, ham and oregano, put them in a bowl with the garlic, lemon zest and tablespoon of olive oil, and mix well. Spread the mix all over the chicken breast under the skin.
Put the chicken in a roasting tin, squeeze over the lemon juice, then pop the spent halves inside the cavity. Generously season the bird inside and out, then roast for an hour, or until the juices run clear (test by poking the tip of a sharp knife into the thickest part of the thigh). Transfer the chicken to a warmed plate, cover with foil to keep it warm, then leave to rest for 10-15 minutes.
Toast the cumin seeds and pimentón in a dry pan.
Set the tin of roasting juices over a low heat, add the toasted spices, chickpeas, vinegar, sultanas and extra-virgin olive oil, and heat gently, stirring; tip in any resting juices from the chicken plate, too.
Take the tin off the heat, then stir in the watercress. Carve the chicken, arrange on a platter and serve with the warm salad on the side.
