1. Lightly prick the sausages all over and arrange in a single layer in a heatproof dish.
2. Blend together the oil, ketchup, mustard and Worcestershire sauce and spread over the sausages.
3. Leave in a cool place for at least 2 hours, turning occasionally.
4. Heat the grill/broiler to moderate.
5. grill/broil the sausages in their dish, basting frequently, for about 15 minutes or until golden brown all over.