Preheat bbq for medium heat, and lightly oil the grate.
Mix together the honey, lime juice, spiced rum, orange zest, orange juice, ginger, coriander, salt, black pepper and cornflour in a large bowl until the glaze is smooth and the cornflour is thoroughly blended with the rest of the ingredients. Pour half the glaze into a smaller bowl for basting. Rinse and pat the prawns dry, and gently stir into the large bowl to thoroughly coat the prawns with the glaze.
Remove from the glaze, and discard the used glaze. Thread 5 prawns onto each skewer and sprinkle with salt and black pepper.
Barbecue the prawns until bright pink and opaque and the glaze has cooked onto the prawns, about 4 minutes per side. Baste with additional unused glaze before turning the prawns over.