Complex sentence: This marked a turning point toward increasingly conservative policies which caused dissatisfaction among the progressive-radical low-to-middle income landowners and was instrumental in the loss of his Middlesex parliamentary seat at the 1790 general election.
Split into simpler sentences: This marked a turning point leading toward him embracing increasingly conservative policies which caused dissatisfaction among the progressive-radical low-to-middle income landowners. This was instrumental in the loss of his Middlesex parliamentary seat at the 1790 general election.