The Earl of Derby was originally a Whig who was lured to cross the divide thanks to the more open and progressive policies of Sir Robert Peel in 1837. In 1841 he was appointed Secretary of State for War and the Colonies where he was responsible for issues such as the 'Opium Wars' with China.
Derby would resign from Peel's government when he disagreed with him over repealing the Corn Laws. He was to became a focus for the protectionists in the Conservative and so would be the natural heir to those Conservatives who felt betrayed by Peel. However, his first ministry in 1852 could not bridge the gap between the two groups of Conservatives and so quickly fell by the wayside becoming known as the 'Who? Who? Cabinet'.
Derby's second administration, 1858-59, achieved more, although it was still dependent on divisions among the opposition for survival. One action was the India Bill of 1858, which transferred control of the East India Company to the Crown in the aftermath of the Indian Mutiny. However, in 1859 Derby's attempt to widen the franchise led to his government's downfall.
Derby returned to government as PM for a third time in 1866. His final government was responsible for the landmark Second Reform Bill of 1867, a milestone in the democratisation of Britain. Ill health forced Derby's resignation the following year, and led to his death in 1869.