In a small bowl, combine the parsley, basil, oregano, rosemary, salt and pepper. Stir in the lemon juice and olive oil to form a paste.
Preheat the oven to 190°C. Rinse the chicken; drain and pat dry. Truss the chicken, and place it, breast side up, on a rack in a roasting pan. Rub the surface of the chicken with the herb mixture.
Roast the chicken, basting with the pan juices every 15 minutes, for 1–1 1/4 hours, or until the juices run clear, with no tinge of pink when a fine skewer is inserted into the thickest part of the flesh between the thigh and the leg.
Remove the chicken and allow it to rest while you make a clear gravy. Tilt the roasting pan, spoon off the fat from the juices and discard. Add the chicken stock to the juices and boil briskly, stirring and scraping any browned residue off the bottom of the pan, until the liquid has reduced by about half. Turn the heat to low and whisk in the butter, a little at a time. Adjust the seasoning and transfer the gravy to a heated gravy boat or jug.
Garnish the chicken with rosemary sprigs and lemon wedges and serve with the gravy and a selection of steamed vegetables.