Beilby Porteus was the son of Robert Porteus, a native of Virginia, US who had returned to England in 1720. Educated at York and Ripon, he was a classics scholar at Cambridge University and was ordained as a priest in 1757. Appointed Chaplain to the King in 1769, Beilby Porteus became Bishop of Chester in 1776 and subsequently was appointed Bishop of London in 1787.
One of many Porteous/Porteus family members who were churchmen, Beilby belonged to the evangelical wing of the Church of England. He was a prolific preacher and writer, and a lifelong friend and supporter of William Wilberforce, the abolitionist.
Beilby himself took a deep interest in the plight of West Indian negro slaves, preaching and campaigning actively against the slave trade. He was active in the establishment of Sunday Schools in every parish, an early patron of the Church Missionary Society and one of the founder members of the British and Foreign Bible Society.