Mantell was the eldest son of George Mantell of Faringdon, Berkshire, a medical doctor. Born on 1 December 1813, Mantell was educated at Radley College and was a student at Middle Temple from 1 November 1841.[1][2]
Mantell was a Queen's Advocateinthe Gambia from 1841 to 1847, before being called to the bar on 18 June 1847. He then became chief justice and judge of the Vice-Admiralty Court of the Gambia, serving from 1847 to 1866. He was knighted on 9 August 1867, and became a stipendiary magistrate for Manchester in 1869. He served until 1885. He also served as a Justice of the Peace for Lancashire.[1][2]
Mantell married Susan Finch in 1838 at St Martins in the Fields, and they had one daughter in 1850, Laura. It has been suggested that Susan died in The Gambia.[2] Mantell re-married to Elinor Knight in January 1867, the daughter of Charles Hitchcock, a medical doctor from Devizes, Wiltshire.[1]
