Put a large pan filled up to the top with water on to boil. Add salt. Once boiling add spaghetti and cook for 10 minutes, or until al dente. Near the end of the time, reserve a mugful of starchy cooking water.
Whilst your pasta is cooking, gently 1 tablespoon of extra virgin olive oil in a frying pan. Peel and slice garlic. Add the garlic to the oil and let it sizzle a little for about 3 minutes - don't let it colour or it will taste bitter.
Add the tin of anchovy fillets - along with the oil. Break them up with a wooden spoon. They will melt into the sauce so no need to chop. Sizzle for 2 more minutes.
Tip in the tomatoes and turn up the heat. Now the tuna - with oil. Toss them every now and then. Squeeze of lemon and pepper. Let it gently bubble for the rest of the pasta cooking time, i.e. 5 more minutes.
Drain the pasta (don't forget to reserve the liquid) and tip into the sauce. Toss, adding a slosh of cooking water. Now for the basil leaves - whole. Toss some more. Keep stirring and tossing until the water and oils have pretty much been hovered up by the silken strands. Serve with nothing more than black pepper and a satisfied grin; you're totally winning the teatime war!