Heat the oil and garlic in a wide saucepan. When you can smell the garlic, add the celery and sauté over gentle heat until it softens and turns pale gold. Add the tomatoes, season with salt and a twist of pepper and simmer for 10–15 minutes, breaking up the tomatoes with a wooden spoon. Add the tuna, breaking up the chunks with your wooden spoon. Add 3 tablespoons of hot water, let it come to the boil and then stir in the basil, parsley and olives. Simmer for a few minutes before removing from the heat. The sauce should not be too dry, so add a few more drops of water if necessary.
Cook the pasta in a large pan of salted water, following the packet instructions. Drain, keeping a cupful of the cooking water. Toss the pasta with the sauce, adding a little of the cooking water if necessary to help the sauce coat the pasta. Serve immediately, with a drizzle of olive oil and a little black pepper for the adults.