Complex sentence: The key breach came over the 1921 Licensing Bill which raised the question of whether Monmouthshire was part of Wales or England had become a particularly significant local issue, with the Liberals tending to the former position and the Conservatives to the latter.
Split into simpler sentences: The key breach came over the 1921 Licensing Bill which raised the question of whether Monmouthshire was part of Wales or England. This had become a particularly significant local issue, with the Liberals tending to the former position and the Conservatives to the latter.