Mix all the marinade ingredients in a shallow bowl. Add the prawns to the marinade, turning to coat thoroughly. Cover and leave to marinate for 1 hour.
Put the rice in a large saucepan of boiling salted water and cook for 12—15 minutes or until just tender. Pour into a colander to drain.
Meanwhile, cook the peas in a separate saucepan of simmering salted water for about 5 minutes or until they are just tender. Drain the peas thoroughly.
Drain the prawns, reserving the marinade, and thread on to 4 metal skewers, alternating with the bacon rolls.
Cook on a hot barbecue for 6—8 minutes, turning the skewers several times and brushing the prawns and bacon with the remaining marinade, until the prawns are tender and cooked through and the bacon is crisp.
Meanwhile, melt the margarine in a saucepan, add the mushrooms and fry gently for about 3 minutes, until soft.
Stir the rice and peas into the pan and season to taste. Pile the rice mixture on to a heated serving dish and serve with the kebabs arranged on top.