Complex sentence: In the 1975 election he was elected to Parliament as the National Party MP for Awarua, thus, with Ben Couch becoming only the second and third Māori (after Sir James Carroll) to win a general (ie non Māori) seat.
Split into simpler sentences: In the 1975 election he was elected to Parliament as the National Party MP for Awarua. So Austin and Ben Couch became only the second and third Māori (after Sir James Carroll) to win a general (ie non Māori) seat.