William Forster was a preacher, Quaker elder and a fervent abolitionist. He was an early member of the British and Foreign Anti-Slavery Society in 1839. It was William and Stephen Grellet who introduced Elizabeth Fry to her life's work with prisons, but it was William's brother, Josiah, who accompanied Fry on her tour and inspection of prisons in France.

Josiah Forster was an English teacher and philanthropist. He was an early member of the British and Foreign Anti-Slavery Society in 1839 and a supporter of the British and Foreign Bible Society. Both he and his wife were senior figures in the British Quakers.