Preheat oven to 430°F. Line a baking tray with foil, or lightly grease a roasting pan.
Pour the olive oil, and lemon juice over the chicken, under the skin and inside the cavity. Season chicken liberally on the outside and inside the cavity with salt and pepper.
Rub the minced garlic and ginger over the chicken, mixing all ingredients together over the chicken and under the skin.
Stuff the rosemary sprigs into the chicken cavity. Tie legs together with kitchen string.
Place breast-side up into baking tray or roasting pan. Roast for 1 hour and 15-20 minutes, basting halfway through cooking time, until juices run clear when chicken thigh is pierced with a skewer.
Baste again, then broil for a further 2-3 minutes, until golden.
Remove it from the oven, cover with foil and allow it to stand for 10 minutes before serving.