Add the linguine to a pan of boiling salted water and cook according to packet instructions.
Meanwhile, put a large frying pan on a high heat and add a few good lugs of olive oil. Once hot, add the garlic, chilli, capers and parsley stalks. Cook for a couple of minutes until just starting to colour. Add the herring strips to the pan and cook for 2 minutes. They will start to break up but don’t worry. Add the tomatoes and squeeze in the juice of a lemon.
Use tongs to transfer the cooked linguine straight into the frying pan, bringing a little of the cooking water with it. Add the butter, if using, and toss everything together in the pan. Have a taste, season with salt and pepper, add most of the parsley leaves and a lug of extra virgin olive oil. Mix again – use tongs if you need to – then transfer to a large platter. Scatter over the remaining parsley leaves and whack it in the centre of the table so everyone can tuck straight in.