Soak the beans in cold water overnight.
Drain, place in a pan, cover with fresh cold water and bring to the boil.
Boil rapidly for 10 minutes, then simmer for 45 minutes.
Drain and cool.
Place in a salad bowl, add the sweetcorn, onion and French dressing and toss well to mix.
Sprinkle with the chopped parsley just before serving.