Plunge the pasta into a large saucepan of lightly salted boiling water. Return to the boil and cook for 10–12 minutes until al dente. Drain well and return to the pan.
Meanwhile, heat the oil in a frying pan, add the leeks, garlic and salt and pepper to taste and cook gently for 5 minutes.
Flake in the tuna and cook, stirring, for 1 minute. Add the wine, bring to the boil and boil until reduced by half. Stir in the cream and heat through for 2–3 minutes.
Add the tuna sauce to the pasta with the parsley and stir over a medium heat for 1 minute. Serve immediately with a rocket salad.