Meanwhile, bring a large pan of salted water to the boil and cook the pasta until al dente according to the packet instructions. Drain loosely, saving a cupful of the cooking water.
Once the sauce has thickened, stir in the mackerel and heat for a couple of minutes to warm through, then stir in the pasta with a splash of the cooking water and toss well to mix. Sprinkle with the parsley and serve with lemon wedges for squeezing.
