Place the wine and leeks in a large, heavy saucepan. Add the mussels, cover pan and bring to a boil over medium-high heat. Reduce heat to medium and cook, covered, until mussel shells open, 3 to 5 minutes. Use tongs to transfer mussels to a bowl, discarding any that have not opened. Add Pernod to cooking liquid and bring to a boil. Boil for 2 minutes, then reduce heat to medium and stir in cream. Simmer for 2 minutes, then stir in pimento and 2 tablespoons of the parsley. Season lightly with salt and generously with black pepper.
If mussels have cooled too much, return them to the cooking pan with the broth, cover and simmer a minute or so until reheated. Divide mussels between 4 large, shallow soup bowls and spoon broth and vegetables over them. Sprinkle with remaining parsley.