Remove sausage meat from skins. Heat the oil in a large frying pan and add the sausages, breaking them up with a wooden spoon. Add the tomato puree, stir well and fry for 1-2 mins.
Add the white wine, let it sizzle and die down then add the tomatoes. Break them down with a fork, together with any large pieces of meat. Add capers and olives, stir, then leave to simmer for about 15 mins.
Meanwhile, boil pasta until al dente. Spoon 2-3 spoonfuls of the cooking water into the sauce. Drain pasta and return to the pan. Check the sauce for seasoning then pour over the pasta. Add half the parsley, mix and leave to stand for a couple of mins.
Mash feta roughly with a fork. Spoon pasta onto warm plates, crumble over feta and rest of parsley.