Given the following context:

The general impact of Olney Hymns was immediate and it became a widely popular tool for evangelicals in Britain for many years. Scholars appreciated Cowper's poetry somewhat more than Newton's plaintive and plain language driven from his forceful personality. The most prevalent themes in the verses written by Newton in Olney Hymns are faith in salvation, wonder at God's grace, his love for Jesus, and his cheerful exclamations of the joy he found in his faith. As a reflection of Newton's connection to his parishioners, he wrote many of the hymns in first person, admitting his own experience with sin. Bruce Hindmarsh in Sing Them Over Again To Me: Hymns and Hymnbooks in America considers "Amazing Grace" an excellent example of Newton's testimonial style afforded by the use of this perspective. Several of Newton's hymns were recognised as great work ("Amazing Grace" was not among them) while others seem to have been included to fill in when Cowper was unable to write. Jonathan Aitken calls Newton, specifically referring to "Amazing Grace", an "unashamedly middlebrow lyricist writing for a lowbrow congregation", noting that only twenty-one of the nearly 150 words used in all six verses have more than one syllable.William Phipps in the Anglican Theological Review and author James Basker have interpreted the first stanza of "Amazing Grace" as evidence of Newton's realisation that his participation in the slave trade was his wretchedness, perhaps representing a wider common understanding of Newton's motivations. Newton joined forces with a young man named William Wilberforce, the British Member of Parliament who led the Parliamentarian campaign to abolish the slave trade in the British Empire, culminating in the Slave Trade Act 1807. However, Newton became an ardent and outspoken abolitionist after he left Olney in the 1780s; he never connected the construction of the hymn that became "Amazing Grace" to anti-slavery sentiments. The lyrics in Olney Hymns were arranged by their association to the Biblical verses that...

answer the following question:

What is the last name of the parliament member who led the campaign to end slave trade with the man who wrote the Olney Hymns? 

Wilberforce