Prick the chicken all over and make a few slits about 2cm/¾in long on the skin. Mix all the remaining chicken ingredients into a smooth paste and rub the marinade generously all over the chicken skin. Cover and refrigerate for eight hours or overnight.
Preheat the oven to 180C/350F/Gas 4. Place the chicken in a roasting tin and cover with foil. Roast in the centre of the oven for 1½ hours. Halfway through cooking, baste with a little of the marinade.
Remove chicken from the oven and leave in a warm place to rest for 20 minutes.