Complex sentence: In the 1890s, two successive Governors, the Earl of Onslow and the Earl of Glasgow, declined to make several appointments to the (since abolished) Legislative Council on the advice of Premier John Ballance, until the Colonial Office intervened in Ballance's favour.
Split into simpler sentences: In the 1890s, Premier John Ballance advised that several new members be appointed to the (since abolished) Legislative Council. Two successive Governors, the Earl of Onslow and the Earl of Glasgow, refused to make the appointments, until the Colonial Office intervened in Ballance's favour.