Preheat oven to 240 C / Gas 9. Lightly grease a roasting tin and place chicken in it.
Season inside of chicken with salt and pepper and top with 3 lemon slices, basil and 3 cloves of garlic. At the juncture of the thighs, prick holes in chicken and insert remaining garlic cloves. Spread remaining lemon slices over chicken and around it. Season outside of chicken with salt and pepper.
Cook in preheated oven until golden brown, about 15 minutes. Reduce oven temperature to 180 C / Gas 4 and cook for about 1 1/2 hours (depending on size of chicken), or until juices run clear. Baste occasionally with juices while cooking.
If skin seems to be getting too dry, cover with foil about 20 minutes before end of cooking.