Final answer:
Wilberforce promoted the abolition of slavery, leading to the Slavery Abolition Act 1833, which was a part of broader nineteenth-century British parliamentary reforms, including the expansion of suffrage and economic liberalization.
Step-by-step explanation:
The parliamentary reform that Wilberforce was promoting was the abolition of slavery. William Wilberforce, a noted politician and philanthropist, was instrumental in the abolition movement against slavery. In 1807, Britain became the first European power to abolish the slave trade; however, it was not until the Slavery Abolition Act 1833 that slavery itself was banned in all British colonies. This significant reform and moral victory were part of a series of reforms in British politics designed to update and modernize the state, including the expansion of suffrage through the Reform Bills and economic reforms like the repeal of the Corn Laws and the implementation of free trade policies.