Manning was born at Totteridge, Hertfordshire, the third and youngest son of William Manning, a West India merchant, who served as a director and (1812–1813) as a governor of the Bank of England, and who sat in Parliament for some thirty years, representing in the Tory interest Plympton Earle, Lymington, Evesham, and Penryn consecutively. From this, however, he resigned in 1832, his thoughts having turned towards a clerical career under Evangelical influences, including his friendship with Favell Lee Mortimer, which affected him deeply throughout life.