Cook the pasta in salted water until al dente, set aside approx. 50 ml of the cooking water, drain the pasta and return to the pan. Stir in the butter, cover and set aside.
Heat the oil in a frying pan. Reduce the heat, fry the lobster on a medium heat for approx. 1 min. on each side. Add the garlic, onion and tomatoes, fry for a further 4 mins. Pour in the port, reduce to half the amount. Remove the lobster, break up the shell, remove the lobster tail, cut into pieces. Add the lobster to the tomatoes along with the butter, the reserved cooking water and the pasta, heat gently and season.